PLKSTIODOW. 



PLEURONECTID.B. 



Skeleton of Plaioiatirtu iMiehtdeinu restored. (Conyboare principally.) 



P. &mdkyp*dyliu, Owen ; P. cottatut, Owen ; P. dadieomtu, Owen ; 

 P. rvponu, Owen ; P. grandit, Owen ; /'. tndiantcritu, Owen ; and P. 

 qffou, Owen. 



Dr. BuckUnd truly observes that the discovery of this genus forms 

 one of the most important additions that geology has made to compa- 

 rative anatomy. " It is of the Pletiotaurtu," he says " that Cuvier 

 asxirti the structure to have been the most heteroclite, and its cha- 

 racters altogether the moot monstrous that have been yet found amid 

 the ruins of a former world. To the head of a lizard it united the 

 teeth of a crocodile; a neck of enormous length, resembling the body 

 of a serpent; a trunk and tail haying the proportions of an ordinary 

 quadruped, the ribs of a cameleon, and the paddles of a whale. Such 

 are the strange combinations of form and structure in the Plctiotauriu 

 a genni, the remains of which, after interment for thousands of 

 yean amidst the wreck of millions of extinct inhabitants of the ancient 

 earth, are at length recalled to light by the researches of the geologist, 

 and submitted to our examination in nearly as perfect a state as the 

 bone* of species that are now existing upon the earth." Conybeare 

 thus speaks of its supposed habits : " That it was aquatic is evident 

 from the form of its paddles ; that it was marine is almost equally so, 

 from the remains with which it is universally associated ; that it may 

 hare occasionally visited the shore, the resemblance of its extremities 

 to those of the turtle may lead us to conjecture ; its motion however 

 must have been very awkward on land; its long neck must have 

 impeded it* progress through the water, presenting a striking contrast 

 to the organisation which so admirably fits the Ichthyotaurut to cut 

 through the waves. May it not therefore be concluded (since, in 

 addition to these circumstances, its respiration must have required 

 frequent access of air) that it swam upon or near the surface, arching 

 back its long neck like the swan, and occasionally darting it down at 

 the fish which happened to float within its reach ? It may perhaps 

 have lurked in shoal water along the coast, concealed among the 

 sea-weed, and, raising its nostrils to the surface from a considerable 

 depth, may have found a secure retreat from the assaults of dangerous 

 enemies; while the length and flexibility of its neck may have 

 compensated for the waiit of strength in its jaws, and its incapacity 

 for swift motion through the water, by the suddenness and agility of 

 the attack which they enabled it to make on every animal fitted for 

 its prey which came within its reach." (' QeoL Trans.,' vol. i. port 2, 

 p. 388, N. 8.) 



PLE'STIODON. [ScraciD*.] 



PLKTHODOXTUX*. [AMPHIBIA.] 



PLEURA is the membrane which envelops the lungs and lines the 

 cavities of the chest On the walls of each cavity of the chest the 

 llenra Costalis (as it is here called) is formed by a sheet of fine and 

 elastic cellular tissue, loosely attached to the ribs, intercostal muscles, 

 and other subjacent parts. On the exterior of the lung the Pleura 

 Pulmonalis is composed of a thin superficial layer of fine cellular tissue, 

 and a deeper layer of coarser fibrous tissue, which in most of the largo 

 quadrupeds, and in the seal and some other animals, is very elastic, 

 and affords an important assistance in the act of expiration. The sur- 

 faces of the two portions of pleura are continuous with each other at 

 the root of the lung ; each is covered with a delicate layer of epithe- 

 lium ; and they inclose within them a space called the sac of the pleura, 

 into which a small quantity of serous fluid is constantly secreted, which 

 moistens the opposite surfaces of the lung and of the wall of the chest, 

 and permit, their free motion upon each other. [MEMBRANE.] 



I-LKntACANTHUS. fFisaVl 



FLEUKOIlHANCHvKA. [SEMi-PHTLLtDlAKg.] 



I'l.Kl-UOIiHANCHUa PIIII.PIITLLIDIAKS.J 



EUHJBODOVXft Messrs. Dumoril and Bibron make their 

 Iguanieos I'leunxlontc* the first sub-family of the Iguanian Lizards, 

 or Bauriens Eunote*. floUAXlD*.] 



PLEUHONE'CTI DM, a family of Fishes of the order MalaeopUrygii 

 and section SMmduaU*. This family contains the Soles, Flounder*, 

 and Turbot*, and some other fishes, all of which are readily distin- 

 guished by the flattened form of the body, and in having both the eyes 

 on one aid*. This want of symmetry in the form of the head, Cuvier 

 state*, is unique amongst vertebrate animals. The side of the body 

 which is uppermost is always coloured, and might be mistaken for the 

 back of the flah, whilst the opposite side is white. The two sides of 



\ the mouth are unequal, and it is uncommon to find the two pectoral 

 fins equal ; the dorsal and anal fins extend the whole length of the 

 back and abdomen respectively ; the ventrals appear like a continuation 

 of the anal ; the branchiostegous membrane has six rays. 



The PUwranecticUt are divided into the following genera : 



Platata, in which the jaws are each furnished with a single row 

 of obtuse teeth ; on the pharyngeans are generally some teeth like 

 paving-atones ; the dorsal fin is only extended in front to a line with 

 the eye, and leaves, as well as the anal, an interval between it and the 

 caudaL The form of the body is rhomboiclal, and the eyes are usually 

 on the right side. 



P. vulgarii, CUT., the Common Plaice, is usually about a foot or 

 rather more in length ; of a brown colour above, spotted with red or 

 orange ; on the eye-side of the head are some osseous tubercles ; tho 

 lateral line is curved above the pectoral fin ; the body is smooth, and 

 the teeth are blunt and contiguous. 



This fish is very abundant on various parts of the British coast, and 

 is said sometimes to attain the weight of 15 Ibs. 



P. Plesut, the Flounder; P. Limanda, the Dab; and P. micro- 

 cephala, the Lemon Dab, are also examples of the genus Platuta. 



J/ijilioglosrut, Cuv. The species of this genus differ from the Plaices 

 proper in having the body usually more elongated, and the jaws and 

 pharyngeans armed with strong and pointed teeth. 



11. rul'/arif, Flem., the Holibut, is not uncommon on some parts of 

 our coast, and is often exposed for sale in the London market It is 

 usually of large size. One specimen, taken in the Isle of Man, is said 

 to have measured 74 feet in length. In the northern parts of Britain 

 it is called the Turbot : the Holibut however is of a much longer form 

 than the Turbot, and by no means equal to it in flavour. 



Rhomtiuu, Cuv. The species of this genus have the jaws and pharyn- 

 geans furnished with thickly-set small pointed teeth ; the dorsal fin 

 commences immediately above the upper lip, and this fin, as well as 

 the anal, extends very nearly to the tail ; the eyes are generally on the 

 left side. 



The Turbot, Brill, Mullet's Topknot, Bloch's Topknot, the Whiff, 

 and tho Scaldfish, are British examples of the genus Rhombta. 



P. marimuM, Cuv., tho Turbot, next to the Holibut, is one of tho 

 largest of the Plcuronectidai found on our coast, and is the most highly 

 esteemed for the table. The Turbot is of a short and broad form, 

 and rather deeper than many of the flat fishes. Its prevailing colour 

 is brown, and the whole of the coloured side is studded with hard 

 and roundish tubercles ; the lateral line is considerably arched above 

 the pectoral fin, and thence runs straight to the tail. It is called in 

 Scotland the liawn Fleuk and Bannock Fleuk. 



"On the coasts of Durham and Yorkshire," says Mr. Yarrell, "a 

 considerable fishery of Turbot is carried on by the fishermen of 

 Hartlepool and Scarborough with long lines. ... A large portion of 

 the Turbot produced in the English market is taken on or near the 

 various sand-banks between the long line of our eastern shore and the 

 coast of Holland." 



R. vulgarii, Cuv., the Brill, is very similar to the Turbot in appear- 

 ance, but inferior in flavour ; it is common in the markets, and may 

 at once be distinguished by its less broad form, the want of the osseous 

 tubercles on the coloured side of the body, and the colouring, which 

 is reddish or sandy-brown varied with darker brown, and minutely 

 spotted with white. It is moreover a smaller fish. 



Solea, Cuv., contains the Soles, which ore distinguished generally 

 by their more elongated farm and the blunt and rounded shape of the 

 muzzle. The eyes, as well as the colouring, are on the right side ; the 

 teeth are small and confined to that side of the mouth which is opposed 

 to the eyes; the dorsal fin commences in front of the lino over the 

 eyes, and extends, as well as the anal, to the tail-fin. 



Cuvier separates as a sub-genus from the Soles proper those species 

 which have the pectoral fin on the side with the eyes very small, and 

 that on the opposite side either rudimentary or altogether wanting. 

 They are termed Monochinu. 



S. vulgarit, Cuv., the Common Sole, inhabits the sandy shore all 

 round our coast, where it keeps to the bottom, and feeds upon small 

 testaceous animals and the fry of other fishes ; as they will not readily 

 take bait, they are almost entirely caught by trawling. " Eighty- 

 six thousand bushels of Soles were received at Billingsgate-market 



