68 TERRESTRIAL AIR-BREATHING MOLLUSKS. 



The organ denominated genital bladder, from its opening into the 

 vagina, or at the termination of the latter, and in Veronicella from its 

 belonging almost wholly to the female organs, must be considered rather 

 as a portion of the female apparatus than a prostatic sac, as it is called 

 by Owen. By many authors this has been termed the spermatheca, 

 from its supposed function of holding spermatic fluid received from the 

 male organs, and with some reason ; for in several instances I have " 

 found it to contain a tenacious mass, which upon microscopic analysis 

 was found to be composed of spermatozoa. This cannot, however, be 

 considered wholly as its use ; for it secretes a mucoid matter, which 

 may probably facilitate the passage of the ova through the vagina and 

 cloaca. The mucoid matter within the bladder is frequently found to 

 contain immense numbers of an infusorial parasite, which has been de- 

 scribed under the name of Cryptoicus. 1 



The epithelium of the bladder consists of very long, caudate, colum- 

 nar cells, with elliptical, granular nuclei, and a small round nucleolus. 



In comparison of the descriptions of genitalia in this work with those 

 given by foreign authors, it must be remembered that the terms ovary, 

 testicle, etc., are not applied to the same organ. 



In Vol. I. will be found figures of the genital system of many of 

 our species. I have in this volume repeated the descriptions, under each 

 species, and given figures of many not included in the plates of Vol. I. 



OF THE RESPIRATORY AND CIRCULATORY APPARATUS. 



The lung of the Terrestrial Gasteropoda is a simple cavity, with an 

 orifice communicating with the exterior, upon the right side of the 

 body. The surface of this pulmonary cavity in part of its extent, and 

 more particularly near the pulmonary orifice, is covered by a close in- 

 tertexture of blood-vessels. The blood of the body is conveyed directly 

 to the lungs by two principal vessels, the pulmonary arteries, which 

 join the capillary rete of the pulmonary surface. From this rete passes 

 off the pulmonary vein to the heart, which is systemic, and consists 

 of an auricle and ventricle. The auricle receives the pulmonary vein ; 

 from the ventricle passes off the aorta, to be distributed throughout the 



body. 



LIMAX. The pulmonary cavity is situated beneath the mantle, and 

 has nearly the same size and form. It is separated from the visceral 

 cavity by the muscular peritoneum, but contains the rectum, renal 



i Journ. Acad. Nat. Sci. Phila. N. S. Vol. I. 



