558 



LECTURE XXII. 



(c), which IS smaller and more muscular ; to this succeeds a third {d), 



the sides of which are gathered into broad longitudinal 206 



lamellae, precisely similar to those of a ruminant ; and 



to render the analogy still more perfect, a groove is 



found running along the walls of the second cavity 



from one orifice to the other, apparently subservient 



to rumination. The fourth stomach (e) is thin, and 



its walls smooth. This animal feeds on Alcyonia and 



small Zoophytes.* 



The' intestine, after performing a few convolutions 

 in the substance of the liver and generative gland, 

 always more numerous, and of greater width in the 

 herbivorous than in the carnivorous Gastropods, ter- 

 minates, with a few exceptions, at or near the entry 

 of the respiratory cavity on the right side of the 

 body. The anus has a median position in the Doris 

 and Testacella, and terminates on the left side of the 

 body in the Planorbis. 



In the Apneusta the alimentary canal departs so 

 widely from the ordinary gastropodous type, as to 

 have led some anatomists to regard it as a ground for 

 their separation from the class.f Caecal appendages 

 extend from the stomach, which, in most, are ramified, Pieurobranchus. 

 and in some {Eolis, Tergipes, Zephyrina) are continued into the dorsal 

 appendages.;]: But in all there is a rectum, terminating by a vent, 

 which usually opens on the right side of the fore part of the body. 

 The biliary secreting cells, in these little Gastropods, are developed 

 in the walls of the gastric caeca, most abundantly at their blind 



ends.§ 



In the other orders of Gastropods the liver is a distinct and 

 usually bulky gland, subdivided into numerous lobules of a yellowish- 

 brown or brownish-green colour ; so disposed as more or less to en- 

 velope the intestinal convolutions {Jigs. 204. 207. h, h). Its secretion 

 is derived from arterial blood, and is usually poured by one or two 

 ducts into the commencement of the intestine. It is carried, how- 

 ever, into the stomach, near the pyloric orifice in Limax, Helix, 

 Testacella, Doridium ; and even into the oesophagus, in Oncliidium, 

 by two of its ducts, the third opening into the first stomach. The 

 Haliotis not only resembles the Palliobranchiata in the perforation of 



* CCCXXI. 



+ Under the term Phkbenteres, e. g. by Quatrefages, CCCLXII. 

 i CCCXLIII. § CCCLVI. 



