1835.] Transactions of the Linnean Society of London. 389 



the trachea then takes place, by which the tube, ultimately receding, 

 gains the interior cavity of the breast. The bronchiae are two inches 

 long. Such are the peculiarities which characterize this new species. 



Two species of Leucisous, or dace family of fish, are described by 

 Mr. Yarrell, one of which, L. Lancastriensis, was merely noticed 

 by Mr. Pennant as likely to be new under the name of Graining. It 

 is more slender than the dace. In the latter the length is to the depth 

 as 4 to 1, but in the graining as 5 to 1. The head and back are of a 

 pale drab colour, tinged with red ; irides, yellowish-white ; the fins 

 pale yellowish-white. In the dace the back and sides yellowish 

 olive-coloured, tinged with blue ; lower fins pale red, with a smaller 

 number of fin rays in some fins, in others less. It occurs in a stream 

 which rises in Knowsly Park, in the Mersey and in the Alt. L. 

 elongatus, pinna dorsali supra pinnas ventrales posita, caudali profunde 

 biloba, capitis lateribus supra subparallelis ore parvo, dorso lateri- 

 busque superne subrufescenti, isabellinis inferne ventreque argenteis. 



The other species, L coerulevs is quite new. He gives it the 

 English name of Azurine. Its depth is to its length as 7 to 2, 

 resembling the red eye in shape, but is easily distinguished from that 

 species by the silvery whiteness of the abdomen, which in the red 

 eye is of a brilliant golden orange, and also by its white fins, which 

 in the other are vermilion. L ovato-lanceolatus, pinna dorsali pone 

 pinnas ventrales posita, dorso plumbeo, ventre argenteo, pinnis albis. 

 B3D 10 P 16 V9 A 12 C 19. 



Mr. Guilding observes that the Naticidae form a very distinct 

 family from the Neritidae. The former are apparently blind, the 

 operculum has no appendages; their useless tentacula are weak and 

 turned back on the shell, while in the act of creeping the head and 

 its organs are perfectly veiled by a broad expanded hood, the sensible 

 contractile apex of which serves to guide its motions. At first sight 

 they rather resemble the Bullidae. 



He describes and figures two species of Dentalium, viz. D Semi- 

 strioiatum, and D Sowerbyi. Very little is known with regard to 

 this genus. M. Deshayes had previously thrown some light on its 

 history, but its position in the natural system is not yet made out. 

 Mr. Guilding is inclined to place it near patellae. It resembles in 

 its vent the genus fissurella, in its apical fissure the posterior 

 marginal rima of emarginula. 



Dr. Buckland, in that spirit of benevolence with which the writ- 

 ings of naturalists are almost universally inspired, reproves the harsh 

 sentence which has been passed on the sloth by Cuvier and strives 

 to show that this vulgar type of indolence is undeserving the impu- 

 tation of feebleness or imperfection, and still more of the charge of 

 monstrosity ; that it affords a striking example of perfect mechanism 

 and contrivance when viewed in reference to the office it is destined 

 to fulfil, f< the animal being fitted to its state." 



Cuvier has stated that we find in sloths such few relations to 

 ordinary animals that the general laws of existing organizations 



