ZOOLOGY. 497 



Morphology of the ampullariids. — The ampullariids or apple-snails are 

 especially interesting on account of the union of a lung-like breathing 

 apparatus Avith true brauchuie, and this peculiarity is combined with 

 some salient differences from other gasteropods in the development of 

 varfous parts of the body. The shell varies in different forms, being 

 generally subglobose, but in some discoid and like a Pkmorbis, and in 

 others turreted and very much like the shell of the typical viviparids. 

 The anatomy of' such a type must therefore be always of interest. It 

 has been investigatt d again by Mr. E. L. Bouvier. An examination of 

 the nervous system has shown that it is " both chiastoreurous and zygo- 

 neurous." The '' })enis is an appeudageof the mantle, and is innervated 

 by the right pallia! nerve," an interesting fact, as it is " a very rare if 

 not unique arrangement." The epipodium is supplied by the commis- 

 sural ganglia, and not, as had been previously stated, by the pedal; it 

 is consequently a derivative from the mantle, and it becomes thus mani- 

 fest that " the so-called epipodial structures are not all of the same mor- 

 phological significance, for some are appendages of the foot, and others 

 of the mantle or body wall." 



As in the ctenobranchiates or gasteropods bearing pectinated gills 

 generally, " the gill and false gill are innervated by the supra- intestinal 

 branch of the commissure," and, on account of this mode of supj)ly, '^ it 

 may be concluded that in AmpiiUaria and all other ctenobranchs, the 

 gills are the homologues of the left gill and so-called olfactory organ 

 of the zeugobranchs," and not of the right gill of the latter, as most 

 anatomists have considered. Mr. Bouvier concludes that the systematic 

 relations of the ampullariids are with the zygoneurous tceuioglossates, 

 and that the family approaches most nearly to the calyptroeids. Whether 

 this yiew will be generally accepted is perhaps doubtful. (0. R. Acad. 

 Sc. Paris, cm, pp. 162-165 ; J. R. M. S. (2), vi, pp. 949, 950.) 



Cephalopods. 



Relations of the cephalopods. — In the discussion of the morphology 

 and relationship of the cephalopods, Prof. C. Grobben contends that 

 those mollusks are most closely related to the scaphopods or dentaliids, 

 and not to the pteropods, as has been thought by many to be the case. 

 In his latest communication, he has devoted special attention to the in- 

 nervation of the arms as well as their development, and to a compari- 

 son of the type with Dentaliuni. 



In Professor Grobben's opinion, the arms certainly can not be consid- 

 ered as modifications of the anterior portion of the foot, as is abundantly 

 proved by the nerve supply. (1) "The cerebral ganglion is continued 

 downwards round the (]esophagus,"and " a portion of the suboesophagus, 

 more apparently belonging to the pedal gaugl.on, really belongs to the 

 cerebral." (2) "Of the nerve fibers supplying the arms, many undoubtedly 

 terminate in the downward-directed portions of the brain, but others 

 may be traced through the anterior and posterior lateral commissures 

 H. Mis. 600 32 



