4D6 Messrs. Alder and Hancock on a proposed Neiv Order 



and as the species subjected to dissection is one of the most 

 simple forms of the group, it is consequently likely to show any 

 departure from the niolluscan type in the greatest degree. It will 

 be seen, however, that no such extreme degradation as that sup- 

 posed to exist by M. de Quatrefages, is to be found in our little 

 mollusk, whose organization, though showing some interesting 

 modifications, agrees upon the whole with that of the other Gas- 

 teropods. 



Anatomy, by Albany Hancock. 



In describing the anatomy of these animals we shall confine 

 ourselves almost entirely to that of Limapontia nigra, as of it 

 alone have we possessed a sufficient number to warrant our en- 

 tering at all into details on the subject. We would premise, how- 

 ever, that on account of the extreme minuteness of this species, 

 we have been compelled to use the compressor, and to rely on 

 this mode of investigation to a considerable extent. Being fully 

 aware of the danger arising from examinations conducted solely 

 by the aid of transmitted light, especially on animals so highly 

 organized as the Pellibranchiata, we have taken every precaution 

 to avoid error ; and having had an exhaustless supply of speci- 

 mens, we have verified most of the points over and over again. 

 To prevent the confusion arising from the multiplicity of parts, 

 we soon found it necessary to separate the viscera, and it was not 

 until we succeeded in doing this that we made out the genera- 

 tive system, which is of vast complication in this animal. The 

 digestive apparatus is much simpler, and may be almost entirely 

 determined without the aid of the compressor. We observed 

 nearly the whole of this portion of the anatomy in an individual 

 whose skin was rendered transparent by removing the epidermis 

 and pigment cells : the oesophagus and intestine, being tilled at 

 the time with matter, rendering these parts opake, were seen very 

 distinctly ; the two lateral branched vessels forming the biliary 

 organ were also observed in connexion with the sides of the 

 stomach. 



We have said thus much on the mode of investigation, that the 

 authenticity of the following details may be duly estimated. 



The Digestive System opens on the inferior surface of the head, 

 where a small puckered orifice indicates the entrance to a short 

 channel, which leads to a muscular buccal mass (PI. XX. fig. 1 a). 

 This is circular when viewed from above, but, when seen in pro- 

 file, is irregularly quadrate, with a projection in front from the 

 inferior angle. We could not distinguish the least appearance 

 of corneous jaws. The tongue {b) however is very easily seen : 

 it is a prehensile organ, and appears to be placed in the cavity of 

 the mouth as in the Eolididce -, that is, it is bent fr^m behind 



