Miscellaneous* 357 



lated to each other, moveable, and projecting internally, are armed 

 with stiff bristles, regularly arranged in rows, like the hairs of a brush. 

 Other hairs, of larger size and more flexible, spring from the roof of 

 the organ, and from its pyloric appendages. Lastly, its cavity may 

 be divided into two distinct compartments, viz. a short, narrow one, 

 nearly cylindrical, immediately following the oesophagus, and a 

 larger one, anfractuous in form, which communicates with the intes- 

 tine by a contractile circular orifice, surrounded by projecting, 

 ciliated, pyramidal languettes. Thus in most larvae, both of Brachyura 

 and Macrura, the stomach agrees iu structure and position with 

 that of the adult animal. 



In the Phyllosomes the stomach is comparatively smaller, and 

 more elongated and compressed. Instead of being close to the 

 ocular peduncles, it occupies the posterior third of the cephalic 

 buckler. From the upper lamina of this buckler it is separated 

 only by the median or ophthalmic artery ; its lateral surfaces are 

 entirely free, and its lower surfaces rest partly upon the oesophagus. 

 Its cavity is quite undivided ; and its walls, formed by a muscular 

 and a mucous layer, are sustained only by extremely simple carti- 

 laginous laminae. But it presents the stiff bristles which spring 

 from the projecting laminae of the Zoeas, &c., and the vibratile cilia 

 which keep the organic molecules of the animal's food in constant 

 rotation. It also presents the six pyramidal villous languettes sur- 

 rounding the pyloric orifice, and projecting into the intestine. This 

 structure of the pylorus seems to be common to the larvae of Deca- 

 poda. 



The same comparative simplicity of structure is presented by the 

 Intestine of the Phyllosomes. It extends in a straight line from 

 the pylorus to the anus ; it is slender, with its walls a little thicker 

 than those of the stomach ; it is nearly of the same size throughout, 

 but is divided by a valvular constriction into two distinct portions, 

 of which the anterior, which is very long, represents the duodenum, 

 and the posterior, very short, the rectum. The latter terminates in 

 an oblique, oblong anal orifice, furnished with two lips moved by 

 numerous and powerful muscles, which are attached to the sides of 

 the last segment. 



In the Brachyura and some Macrura, the intestine, at birth and 

 even during the ovarian evolution of the embryo, presents, at the 

 pyloric region and at the extremity of the duodenal portion, some 

 small ampullae, which, by subsequent development, become the long 

 membranous appendages of the intestine in the adult. The Phyllo- 

 somes present nothing of the sort, and the liver is the only secretory 

 organ of the digestive apparatus. 



In larvae of which the development is not far advanced, this organ 

 consists of two simple short caeca, springing from the pyloric region 

 at the point where the double vitellary duct of the umbilical vesicle 

 opens, and lying upon the lateral and anterior portions of the cephalic 

 buckler. During development these caeca soon bifurcate, and the 

 two canals thus produced pass between the laminae of the anterior 

 buckler. The inner canal, as it enlarges, becomes dilated into a 



