416 On the Anatomical Structure of 



ART. XXXV. — ox THE AXAT03IICAL STRUCTURE OF GLAXDIXA 



TRUXCATA OF SAY. By Jeffries Wyman, M. D. 



(Communicated November lo, 1843.) 



A KNOWLEDGE of the aiiatomical structure of this animal 

 has been a desideratum, from the time when its external pecu- 

 liarities were announced by Mr. Say, until now. The privi- 

 lege having been lately allowed to me of examining one of 

 the specimens which were forwarded to Dr. Binney, by J. 

 Hamilton Couper, Esq. of Darien, Ga., to whose politeness and 

 zeal for the advancement of natural science this Society and 

 many individuals are indebted for similar favors, advantage 

 was taken of it to make as minute an examination as time 

 would permit. The result of the examination is embodied 

 in the present paper. The opportunity of investigating the 

 anatomy of Bidimus ovadis of ]Mullcr, and Achat hia perdix of 

 Lamarck having occured at the same time, the means were 

 afforded of comparing the structure of the three genera. 



When the animal is removed from the shell, the different 

 organs remaining in the same position as when in the act of 

 crawling, we have exposed anteriorly the head, protruded 

 beyond the principal mass of the viscera, (PI. xxiii. fig. 1.) 

 The viscera are bordered anteriorly by the collar (« of,) behind 

 which is the respiratory cavity, (6 h.) occupying the larger 

 portion of the upper and left lateral surfaces, and after making 

 a single turn behind the viscera terminating on the right side 

 at d. The respiratory and anal orifices are situated just 

 beneath the right extremity of the collar at a. The genital 

 orifice is farther forward, a litde posterior to the upper tenta- 

 cle. The liver, (e c,) forms nearly the whole of the posterior 

 portion of the visceral mass. 



In the general characters of its organization, G. truncata 

 resembles the genera Limax and Helix, but differs from them 

 in the existence of an additional pair of tentacles and a corres- 

 ponding modification of the nerves distributed to them, in the 

 arrangement of the teeth on the tongue, in the complicated 

 form of the stomach, and in some other characters of less 

 importance. 



