477 



LITTORELLA. 



LIVER. 



478 



unfortunately had not studied its external organisation ; he observed 

 however the singular fact that this animal, which lives upon floating 

 plants, quits them sometimes, but holds itself fixed by a thread. 

 [LIMX/EAD^E.] M. Rang dissected some specimens preserved in spirit 

 of wine given to him by that officer, and detected some small glairy 

 masses which appeared to M. Rang to be attached to the foot, and 

 which were easily drawn out to considerable length. M. Rang looked 

 in vain for an operculum, the absence of which establishes a great differ- 

 ence between this genus and Phasianella, and has described two species, 

 different as regards the shell, but with apparently similar animals. 



M. Rang observes that the genus Litiopa, like some others, proves 

 that it is not possible to establish divisions founded on the presence 

 or absence of an operculum. 



LITTORELLA, a genus of Plants belonging to the natural order 

 Plantaginaceee. It is monoecious ; the male flowers stalked ; sepals 4 ; 

 tube of the corolla cylindrical; limb 4-parted; stamens hypogynous; 

 filaments very long. The female flowers sessile ; sepals 3 ; corolla 

 oblong, narrowed at both ends; styles long ; capsules 1 -seeded. 



L. lacuitru, has white flowers ; the fertile flowers sessile ; stalks of 

 the male flower one or two inches long; leaves all radical, linear 

 fleshy, somewhat channeled. It is found on the margin of lakes. 



LITTORINA. [LiTTOBiNiD^.] 



LITTORINIDJE, a family of Gasteropodous Mottusca living in the 

 sea or in brackish water. The animals are bisexual ; they have muzzle- 

 shaped heads provided with tentacular and sessile eyes. Their tongues 

 are long, and armed with transverse bands of teeth, each row consist- 

 ing of a broad and hooked central denticle, flanked on each side by 

 three oblong hooked laterals or uncini. The branchial plume is 

 single ; the foot has a distinct linear duplication in front, and a groove 

 along the sole. The form and appendages of the operculigerous lobe 

 afford important generic distinctions. There are no neck-lobes or lateral 

 cirrhi. The mantle exhibits traces of a rudimentary canal, or respira- 

 tory fold. Members of this group inhabit all regions of the sea, but 

 by far the greater number live near the shore, and a very considerable 

 portion of them are found between tide-marks. 



Liltorina. The species have turbinate shells, solid, sub-conic, or 

 sub-globose, with a short spire ; surface smooth or spirally grooved, 

 protected by a more or less developed epidermis ; mouth subcircular, 

 peritreme entire, outer lip sharp-edged, columellar lip expanded, 

 imperforate ; operculum pyriform, corneous, of few rapidly-increasing 

 whorls ; the spiral nucleus laterally placed. 



The animal has a muzzle-shaped head, with two tentacula, bearing 

 the eyes on bulgings at or near their external bases ; no neck-lobes ; 

 operculigerous lobe without filamentary processes ; foot rounded at 

 both extremities, grooved below for the two posterior thirds of its 

 length ; branchial plume single. They all live strictly between tide- 

 marks, and many of them can exist without inconvenience in localities 

 where the sea only occasionally sprinkles them with its spray. 



The Liltorirue, or Periwinkles, to call them by their popular name, 

 are distributed through the seas of all climates. Fossil species are 

 enumerated likewise from all formations, even the most ancient, but 

 many are placed in this genus which no doubt belong elsewhere. 



L. Neritovlei is small, smooth, ovate, conic, usually more or less 

 black ; whorls much shelving, flattish, or merely convex ; spire short 

 but acute ; mouth angularly contracted posteriorly ; outer edge of the 

 pillar-lip but little if at all concave ; throat very dark. The shell is 

 found on the very edge of tide-marks, and often at considerable dis- 

 tances above it, where only the dash of the spray can moisten it with 

 sea-water. It is common on our rocky shores all round Britain and 

 Ireland, and is distributed all round the coasts of Europe, and extends 

 through the Mediterranean. 



L. littorea is solid, not smooth, yet rarely ridged ; whorls not 

 rounded, but more or less flattened ; base and pillar not so produced, 

 and aperture not so filled up anteriorly, as in L. rudis; outer lip joining 

 the body at an acute angle, and more arched below than above ; pillar- 

 lip not peculiarly broad, usually white, its inner edge for the most part 

 well arcuated. This is pre-eminently the Periwinkle of our shores, a 

 name said to be a corruption of ' petty-winkle.' In Suffolk they are 

 called ' Pinpatches.' Great quantities are sold in London, and eaten 

 on many parts of our coast, after being boiled, when the animal is 

 extracted by means of a pirn This is a poor man's delicacy, but by no 

 means to be despised. It inhabits the third sub-region of the littoral 

 zone or belt, between tide-marks, that of which Fucu articulatus and 

 P. nodotu* are the characteristic plants, and is found in every district 

 long our shores. 



L, rudi* is solid, rarely ridged; whorls rounded; spire acute, more 

 or leu abort ; mouth small, more or less rounded, not contracted 

 above, but lessened at the base by the broad confluence of the pillar 

 and outer lip, which latter is rather more arched above than below, 

 and joins the body at nearly right angles; base generally a little 

 produced. This strong shell closely resembles the preceding, but 

 does not attain to its size, and chiefly differs from it in the rouudness 

 of its well-defined proportions. The colour ranges from yellowish- 

 white to orange, and is either uniform or banded with about two or 

 three zones of liver-colour or chocolate, of which one at least is broad. 

 The animal differs from that of the preceding species in being of a. 

 lighter hue, with the exception of the head, which is more uniformly 

 dusky. It is found almost everywhere on stony and rocky shores, 



often in considerable numbers, though not strictly gregarious. It 

 inhabits the first and second sub-regions of the littoral zone ; those 

 of fucus canaliculatus aud Lichina, usually below the next species, 

 and always within the reach of the tide. Its continental range is like 

 that of Littorea. 



L. littoralis is semi-globose, solid, smooth, or at most striolate, the 

 general surface flattiah; body bluntly subangulated above, peaked 

 below in the young ; spire remarkably depressed, its whorls not 

 rounded; pillar-lip decidedly broad. The animal is usually of a 

 bright-yellow colour ; but occasionally, as in a specimen taken in the 

 Isle of Man, is tinged with dusky, and has the tentacula aud muzzle 

 nearly jet-black. This species is abundant all round the British aud 

 Irish coasts, living on Pud between the tide-mark, but more especially 

 inhabiting the third sub-region of the littoral zone, that of Fucus 

 seiTatus, where it is found in company with Trochus cinerarius. It 

 ranges along the shores of the Northern and Celtic provinces on the 

 European side of the Atlantic. 



Messrs. Forbes and Hanley admit the following additional species 

 in their ' British Mollusca" : L. fabalis and L. palliata. L. paiula, 

 L. tenebrosa, and L. sa.ralilin they are disposed to regard as L. rudis. 



The other British genera of this family are Lacuna, of which there 

 are the following species : L. pallidula, L. puteolus, L. vincta, aud L. 

 crassior; Assiminea, including two species, A. Grayana and A. littorea; 

 Ilissoa [RISSOA] ; Jeffreysia [JEFFHEYSIA] ; and Skenea [SKENEA], 



LITUITES, a group of Fossil Cephalopoda, confined to the strata of 

 the Silurian and older systems. The shell is partly straight and 

 partly convoluted, nearly as in Spirula (Lam.). 



LIVER. The liver is the secreting organ or gland by which the 

 bile is formed. Its existence has been traced very low in the scale of 

 animals ; and parts supposed to have been an analogous function havo 

 been found in insects, but their nature is at present a disputed question. 

 The differences in regard to size, form, and colour, which the liver 

 presents in the higher animals (Mammalia, Birds, Reptiles, Amphibia, 

 and Fishes), are of no great importance. 



In man the liver is a large solid viscus, of a reddish-brown or 

 mottled red and yellow colour, situated immediately beneath the 

 diaphragm, in the right hypochondriac and partly in the epigastric 

 region of the abdomen. [ABDOMEN.] When enlarged, it can be felt 

 by the hand applied below the ribs on the right side. It is flattened 

 in the vertical direction, is thinner at its anterior than at its posterior 

 border, and its outline, when viewed from above, is irregularly ovoid. 

 The upper surface, which is convex, is applied to the diaphragm ; the 

 lower, which is irregularly concave, lies above and in coutact with the 

 stomach, large intestine, and right kidney, has attached to it the gall- 

 bladder, and presents two deep furrows, which divide it into several 

 compartments, termed by anatomists lobes. Of the furrows, one 

 running from before backwards (the longitudinal fissure) transmitted, 

 during uterine life, the vessel which conveyed the blood from the 

 placenta to the heart of the foetus ; it afterwards contains merely the 

 cord-like remains of that vessel, now impervious in the greater part of 

 its extent. The second furrow, in the under surface of the liver, is 

 called the transverse fissure, since it crosses the former at right angles, 

 lying however chiefly to its right side ; it serves to allow the entrance 

 of blood-vessels and nerves to the liver and the exit of the bile-duct?. 

 Like other viscera of the abdomen, the liver receives an investment 

 from the lining membrane of that cavity, the peritoneum, which, being 

 reflected from it at different points, forms broad bands connecting the 

 liver with surrounding parts. 



The substance of glands generally is constituted of minute ramified 

 or convoluted canals, closed at their radical extremity, and communi- 

 cating only with the principal duct, by which the secretion is conveyed 

 away, and of a great number of blood-vessels which surround the 

 above-mentioned canals in their whole extent, and afford the com- 

 ponent matters of the secretion ; these matters find their way into the 

 interior of the glandular canals, not by distinct openings from the 

 blood-vessels, but by transudatiou through their walla. In the human 

 subject all other glands than the liver receive one kind of blood only, 

 namely, arterial blood, from which the component 1 ) of the secretion 

 are derived, and the organ at the same time nourished, and the only 

 veins are those wbich convey away the same blood after it is rendered 

 venous by the changes it undergoes in the gland. But the liver, like 

 the lungs in man and the kidneys also in some animals, receives two 

 kinds of blood arterial blood in small quantity, destined principally 

 for the nourishment of the gland, and venous blood in much larger 

 quantity, from which the bile is principally formed. The vessel 

 which brings the arterial blood, the hepatic artery, is small, and comes 

 off the aorta [AORTA], together with the arteries supplying the stomach, 

 spleen, duodenum, and omentum. The venous blood is brought by 

 the portal vein, a large vessel resultiug from the union of all the veins 

 returning the blood from the spleen, omentum, pancreas, aud gall- 

 bladder, and from the viscera directly engaged in the function of 

 digestion, namely, the stomach and intestines. The hepatic artery 

 and portal vein enter the liver at the transverse fissure or furrow of 

 its inferior surface, where the bile-duct issues, and ramify together 

 with the branches of that duct through the substance of the organ. 

 After the materials for the nutrition of the liver itself, and for the 

 secretion of the bile, have been derived from the blood of the two sets 

 of vessels already mentioned, it is returned to the general circulation 



