ALDERIA. 



large, rounded in front, and expanded and reflected upwards at the sides. The orifice of the 

 genital organs is situated very far forward on the right side below the head. 



Professor Allman, in the paper already alluded to, has given some account of the anatomy 

 of this genus, partly founded upon our own observations ; and, from the difficulty of procuring 

 specimens in a fresh state, we have not been able to add much to the original stock of 

 information on this interesting part of the subject. 



The buccal organ (PI. 43, fig. 17) is of an irregular oval form, and unprovided with 

 corneous jaws. The tongue (fig. 17 c, and fig. 18) is narrow, being composed of a single row 

 of long arched plates, (sixteen or seventeen in A. modesta,) each supporting a broad scoop- 

 like tooth or process, which, together with the peculiar form of the plate and the mode of 

 articulation, gives the whole very much the appearance of a minute vertebral column. This 

 tongue is crystalline and resists acids. At the front of the tongue we have observed a few 

 additional teeth ; these may perhaps be of the nature of the spinous prehensile collar found in 

 some of the Dorides, as well as in Limapontia and many other mollusks. 



The stomach is placed rather far back in the body, and from the upper surface gives off 

 folliculated branches, which penetrate the base of the anterior branchial papillae. From below 

 other folliculated branches, connected with the gastric organ, go to the posterior papilke. 

 The glands of the papillae are large, and appear to be highly organised. Further than this, 

 we have not been able to examine the digestive system, which, on the whole, was only 

 obscurely observed. 



We know little of the genitalia, excepting that the apex of the intromittent organ is 

 furnished with a perforated crystalline stiletto (fig. 19 a), curved backwards, and very closely 

 resembling a similar spur-like organ in Limapontia nigra. Hence, perhaps, may be inferred, 

 that the reproductive apparatus is arranged on the type observed in that species. 



