151 



NOTES ON THE ANATOMY OF BULIMULUS AURIS-SCIURI,^ Guppy. 



By S. Pace. 



Bead May Uth, 1894. 



A SHORT time ago the British Museum received a living specimen of 

 BuUmulus am-is-sciuri, Guppy, from Trinidad, which came into my 

 hands for dissection through the kindness of Mr. E. A. Smith, to 

 whom I woukl take this opportunity of retiu^ning my thanks. Since 

 I know of no published description of anything more than the shell 

 of this species, I think it worth while to give the following notes on 

 its anatomy. 



The animal reached me in a sluggish and apparently dying 

 condition; it was in consequence difficult to make much out of it 

 while alive. Its body was of a pale fawn colour, the ocular tentacles 

 being darker, while the labial tentacles were of a brilliant orange- 

 yellow ; the foot was elongated, rounded in front and pointed behind, 

 its under surface showed a central area of a reddish-brown colour, and 

 a paler marginal region sparingly spotted with the same colour- as that 

 of the central area. 



The following (Fig. I.) is a sketch of the "collar" of the mantle 

 viewed from below : it will be noticed that the pulmonary opening 

 is separated by a well-marked upstanding valve into distinct anal 

 and respiratoiy apertures ; the presence of a couple of neck lobes on 

 the mantle is also noteworthy. 



The excretory duct opens immediately above and slightly behind 

 the anus, it is continued as a slight groove into the anal orifice. 



In the anterior part of the mantle cavity, which by-the-bye ex- 

 tended back throughout more than a complete whorl, the pulmonary 

 vessels were thickly beset Avith small spherical structures averaging 

 about '5 mm. in diameter, and of a brownish red colour ; a small 

 portion of this region of the mantle was preserved for microscopical 

 investigation ; examination of sections through it revealed the 

 presence of a central aggregate of yellowish cells in the interior of 

 each of the before-mentioned rounded structures. Similar cells were 

 also loosely diffused through the surrounding tissues of the mantle, 

 more especially towards its outer surface. I have so far been unable 

 to determine whether these yellow cells are, as I am inclined to 

 believe, merely pathological organisms (such as the spores of parasitic 

 fungi) or whether they are specialized elements which are normally 

 present in this creature, and perhaps of assistance in the performance 

 of the respiratory function. It is worthy of note that the lumen 



1 It has been pointed out to me, by Mr. E. A. Smith and our Secretary, that this 

 species is undoubtedly a variety of B. glabcr (Gmel.). 



