417 



LERNEAD^E. 



LEUCISCUS. 



413 



are two pairs of large hooked claw-like members. Length, one-fourth 

 of a line. 



The female fixes itself to the fins and gill-covers of the Cod and 

 Haddock, and is most probably the most common species of our seas. 

 (Johnston.) 



2. A. rugosa,. Body nearly of a square shape, a little emarginated 

 on each side. Head small ; neck slender, and nearly cylindrical. A 

 rounded tubercle on the middle line represents the abdomen. Ovaries 

 rather larger than the thorax, nearly cylindrical, or slightly club- 

 shaped. Length, about 3 lines. 



Found in the mouth of the Gadiis cettarius. 



Tribe III. Anckoraceracea. 



Females : Attached to their prey by the anterior extremity of 

 their body only, thrusting the entire head into the tissues of the 

 animal to which they adhere, and being retained there by means of a 

 kind of horns, which are various in form, and spring from the poste- 

 rior part of the head. No antenna). Only one pair of foot-jaws, 

 which is simple and hooked. Feet either very small or often wanting 

 altogether. 



Males : Very small. Body glot 'ilar, and more imperfect than in 

 the preceding tribes, having no distinct thorax, and no rudiments of 

 feet behind the appendages which represent the foot-jaws. 



Family I. Penelladce. 



Several pairs of feet situated on the under surface of the body near 

 the head, but very small and rudimentary. 



Genus Lerneonema, 



Body long, slender, narrowed anteriorly in the form of a neck, 

 which is terminated by a swollen head furnished with two or three 

 simple curved horn-shaped appendages. Abdominal portion of body 

 of inconsiderable length, and simple. Oviferous tubes long and 

 slender. 



1. L. ipratta, the Eye-Sucker. Body slender, considerably larger at 

 the posterior extremity. Head of tolerable size, rounded, and pro- 

 vided with two narrow rather hooked horns at its back part, 

 directed backwards. The head is connected to the body by means 

 of a long and very slender cylindrical neck, which is furnished with 

 about a dozen constrictions, which make this part of the body appear 

 as if it were beset with an equal number of rings or knobs. 



A short distance beneath the head it is very narrow, gradually 

 increasing in size as it joins the body. Abdominal portion small, 

 blunt, and obliquely truncate. The ovarian tubes are very long and 

 slender, about as long again as the whole body of the animal. Length 

 of the body about an inch ; ovaries one inch and a half. 



It is found attached to the eyes of Sprats, 



2. L. encrtuicoli. Body cylindrical, shorter than the preceding, and 

 of about the same size at both extremities. The neck is long and 

 slender, quite smooth, and destitute of the constrictions which mark 

 so decidedly the preceding species. The neck is white, and the body 

 is of a brown horny colour. 



The abdomen is like that of the preceding, and the ovarian tubes 

 are long and slender, at least twice the length of the body. Tin-ton 

 describes the ovaries as " clear white." Perhaps they may be" so in 

 the living animal, but in the specimens preserved in spirits they are 

 of exactly the same colour as the body. In one specimen however 

 one of the tubes is broken, and the ova have escaped, and in this the 

 tube is white. Length of the body about half an inch ; ovaries fully 

 one inch. 



It is found attached to the bodies of the Clupea encraticolui and 

 C. ipratttu. 



Family II. Lemcoccradte. 



No vestiges of feet on under surface of body, nor any appendages 

 representing them. 



Oenus 1. Lemeocera. 



Body long and slender ; head furnished with horn-shaped append- 

 ages, which are simple and symmetrical in form. Ovarian tubes 

 straight, and of moderate length. Abdomen very small. 



L. cyprinacea. Head furnished with four horn-shaped appendages, 

 which are somewhat long and slender. The two outer or posterior 

 are bifurcated ; the anterior simple. 



The thorax is very slender anteriorly, forming a long neck, but 

 becomes much broader posteriorly, and when it terminates in the 

 small abdomen appears obliquely truncate. The oviferous tubes are 

 cylindrical, and rather long. The length of the whole animal is 

 about 8 lines. 



It is found on the eids of the Carp, Bream, and Roach, in many of 

 our ponds and rivers, in great abundance. 



Genus 2. Lernea. 



Body more or less twisted, and outr<5 in appearance. Head furnished 

 with horn-shaped appendages, which are irregularly branched. Ovarian 

 tubes twisted into round masses, and placed under the posterior portion 

 of the body. Abdomen of considerable size. 



HAT. HUM. DIV. VOL. IIL 



The genus Lcrnea is now restricted within very small limits. Estab- 

 lished by Linnaeus upon the L. branchialis, it is at the present day 

 confined to that species and one or two others. 



L. branchialii. Head rounded, and furnished with three horn- 

 shaped appendages, each of which is divided at the tip into three 

 short branches. 



The anterior portion of the thorax is long, cylindrical, and very 

 slender, like a long narrow neck, while the body itself is very much 

 swollen in the middle, and abruptly twisted upon itself in the form 

 of the letter S. 



The abdominal portion of the body is long, blunt at the extremity, 

 and of considerable size. The ovarian tubes are slender, and very 

 much twisted. 



The whole animal is about an inch and a half in length, and is of a 

 very firm consistence, being hard and horny. 



It is found on the gills of the Cod. 



(Baird, History of British Entomostraca ; Milne-Edwards, ffittoire 

 Naturelle des Crustacea.) 



LESTRIS. [LARID.E.] 



LETTUCE. [LACTDCA.] 



LEUC^ETHIOPES. [ALBINO^.] 



LEUCHTENBERGITE, a Mineral occurring in large but not per- 

 fectly developed crystals in the form of the rhomboid. Colour yel- 

 lowish in masses, but in thin laminae white. The texture lamellar. 

 Lustre pearly. Transparent iu small crystals. Hardness between 

 calc-spar and selenite ; is impressed by the nail. Feels greasy. Spe- 

 cific gravity 2'71. It is found in the Schischmiusk mines in the district 

 of Slatoust. The following is its analysis by Komoueu : 



Silica 34-23 



Alumina 16'31 



Magnesia 35'GO 



Peroxide of Iron . . . . . . 3'33 



Lime 1-75 



Water 8'68 



99-90 



LEUCI'SCUS, a genus of Fishes of the family Cyprinido:, and 

 section Abdominalea. This genus, which was established by Klein, 

 contains numerous species, of which the Roach, Dace, and Bleak 

 afford familiar examples. The characters which distinguish them 

 from others of the Cyprinidae, or Carp tribe, consist in the compara- 

 tive shortness of the dorsal and anal fins, and the want of strong 

 spiny rays at the commencement of either, the simple lips, and 

 deficiency of barbules about the mouth. The various species of 

 Leucitcus are divided into two sections, according to the position of 

 the dorsal fin. Firstly, those in which this fin is situated immediately 

 above the ventral, as in the Roach, Dace, &c., and, secondly, those 

 species in which the dorsal fin is placed above the space intervening 

 between the veutrals and anal, as in the Chub, Rud, Bleak, &c. 



L. rutilus, Cuvier, the Roach, is common in most parts of Europe, 

 swims in large shoals, and frequents rivers, lakes, &c. ; preferring 

 somewhat still and deep waters, feeding upon worms and aquatic 

 vegetables. It usually attains from 12 to 15 inches in length. The 

 length of the head, compared with the whole length of the fish is as 

 one to five ; the depth, at the commencement of the dorsal fin, is to 

 the body alone (without the head or tail) as two to five. The number 

 of the fin-rays are dorsal, 12; pectoral, 17; ventral, 9; anal, 13; 

 and caudal, 19. The scales are large, and the number forming the 

 lateral line is 43 : the number of scales in the oblique line is 11 ; the 

 colour of the back and upper part of the head is bluish-green or dusky 

 green, becoming lighter on the sides of the body, and shaded into 

 silvery- .vhite on the belly. The dorsal and caudal fins are dusky, 

 tinged with red ; the anal, pectoral, and ventral fius are bright-red ; 

 the irides bright-.yellow. 



L. vulgaru, Cuvier, the Dace, is more slender and elongated than 

 the Roach ; the scales are proportionately smaller ; the mouth is 

 more deeply cleft, and the eye is not so large. The length of the 

 head compared with that of the head and body, not including the 

 tail, is as two to nine ; the depth of the body, compared to the whole 

 length, is as one to five. The number of scales composing the lateral 

 line is 52 : there are eight scales in the oblique line above it, and 

 below the lateral to the ventral fin there are four. The dorsal fin 

 commences rather behind the middle of the body, whereas in the 

 Roach it is exactly half way between the nose and the base of the 

 tail fin. The colouring of the upper part of the head aud back is 

 dusky-blue, becoming paler on the sides of the body, and shaded into 

 silvery-white on the belly. The dorsal and caudal fins are pale-brown ; 

 the pectoral, ventral, and anal are almost white, but tinted with pale- 

 red. The fin-rays are dorsal, 9 ; pectoral, 16; ventral, 9 ; anal, 10 ; 

 and caudal 19. The habits of the Dace are very similar to those of 

 the Roach. It is found in Italy, France, and Germany, as well as 

 our own country, generally frequenting the deep clear water of quiet 

 streams. 



" L. Dotula, Cuvier, the Dobule," says Mr. Yarrell, " is found in 

 the Oder, the Elbe, the Weser, and the Rhine, as well as in the smaller 

 streams which run into them." As yet however but one specimen 

 has been found in this country, and was fortunately caught by the 

 author of the ' History of British Fishes,' while fishing, in the month 

 of August, 1831. in the Thames, below Woolwich. It is of a slender 



2 E 



