MeO bE U.S Cox. 

OrpErR GASTEROPODA. 
Genus ATHORACOPHORUS—(Goutp.) 
Corpus limaciforme, supra convexum, retrorsum attenuatum, requiescens 
sptrale, pallio a soled discreto ubique tectum, clypeo carens ; foramine 
pulmonah submediano, inoperto; tentaculis binis brevibus, conicis, 
oculiferis, ad apicem bulbosis, haud omnino retractilibus ; dorso sulco 
mediano ramoso impresso. Lamina calcarea nulla. 
Body limaciform, depressed, convexly rounded above, gradually 
tapering backwards, coiled when at rest, covered throughout by the 
mantle, which is distinguished from the foot by a faint groove. 
Clypeus entirely wanting, the pulmonary aperture on the right side, 
near the median line, entirely unprotected; a delicate channel runs 
along the back, with numerous lateral branches. ‘Tentacles only two, 
short, dilated at base and tip, not wholly retractile. No shell. 
The animal on which I have founded this genus was evidently 
observed by Quoy and Gaimard, and was described in the Voyage of 
the Astrolabe under the name of Limaz bitentaculatus, and indicated 
by them also as the type of a new genus. No other one of the Lima- 
cide has the position of the respiratory aperture so near the dorsal 
line, or so completely exposed, like a mere perforation. Nor am I 
aware that any one has the habit of coiling itself up, when at rest, in 
the manner delineated. ‘These characters, together with the existence 
of only two tentacles, have induced me to institute the genus. 
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