TEBENXOPIIORUS. 461 



dry, diminishes in bnlk more than one half, and dies. We have 

 seen but three specimens. They were very active in their move- 

 ments, and one of them suspended itself by a thread of mucus, in 

 the manner of the Limaccs. Our specimens were found in Ver- 

 mont. Dr. Gould has recognized this or a similar species near 

 Boston. 



It is quite possible that this is one of the species descril)ed by 

 Rafmcsquo, but from the i)overty of his descriptions we are unable 

 to identify it with either of them. 



When Dr. Binney for the first time procured this animal, not 

 l)cing aljle to distinguish the separation of the margin of the mantle 

 from the edge of the foot, he felt assured that it must be a species 

 of Ralincsque's genus Philomijcus, and he accordingly described it 

 as such. Having an oiiportunity since that time of examining sev- 

 eral of them, he noticed, on throwing some of them into alcohol 

 for preservation, that the contraction caused by the liquor revealed 

 and detached the mantle from its adhesion. Its characters, there- 

 fore, correspond with those of the present genus. It is by no means 

 certain, however, that it may not prove to be the young of the pre- 

 ceding species. 



Since the above was written Morse has published (Journ. Portl. 

 Soc. i. 8) a figure of the jaw and lingual membrane of this species 

 which he believes to differ sufficiently from those of T. CaroUnensis 

 to warrant its generic distinction. I have hesitated to adopt his 

 name PaUifcra until his observations shall be confirmed by others.* 

 He describes the jaw as arcuate, ends rounded, blunt, anterior sur- 

 face with stout costoe, strongly dcnticulating the concave margin. 

 The lingual membrane he describes as composed of one hundred 

 and fifteen rows of one hundred and thirteen teetli each (56-1-56) ; 

 centrals tricuspid, laterals bicuspid, uncini with three or four cusps 

 or serrate. 



Order LIMNOPHILA. 



Eyes sessile; tentacles sub-cylindrical or flattened, simply con- 

 tractile. Operculum wanting. Animal usually lacustrine or fluvia- 

 tilc, sometimes marine or littoral, rarely terrestrial. 



All the known families of Limnophila are represented in this 

 country. Their habits arc described under each. 



* The more so as he fipfures the jaw and tonjjae of an Arhn for tliose of Limnr arp-pntit. 

 I have detected errors of my own of tliis kind, arising from incorrectly labelling extracted 

 jaws and tonii^nes. — W. G. B. 



