ANATOMY AND CLASSIFICATION OF THE ABENICOLID^. 457 



former species the anterior achaetous region of the body is 

 longer. The oesophageal pouches in this species and in A. 

 Grubii are definitely divided into a globular anterior portion 

 and a thinner hollow stalk, by which they communicate with 

 the cavity of the oesophagus (figs. 44, 45). The pouches con- 

 tain a neutral greenish liquid, but they often have a pink 

 tinge owing to the large amount of blood contained in their 

 walls. The intestine of A. Grubii and A. ecaudata is not 

 drawn out as in A. marina into lateral wings by the septa 

 of the posterior portion of the animal, but is of almost 

 uniform diameter throughout (see fig. 44) . 



There is one constant and striking point of difference 

 between the alimentary canal of A. Claparedii and that of 

 any other species, viz. the presence of multiple oesophageal 

 pouches. These are placed in the usual position on the oeso- 

 phagus, about midway between the third diaphragm and the 

 heart, and are different in shape from those of any other species. 

 Sometimes they are little more than hollow papillae about 

 2 mm. in length ; more usually they are finger-shaped, and 

 may be even more elongated, almost filiform structures, at- 

 taining a length of about 10 mm. to 12 mm. They often have 

 a moniliform appearance (see figs. 26 to 28). In the specimen 

 drawn in the dissection there are two pouches on each side, 

 an inner smaller one about 3 mm. long, and an outer one 

 about 5 mm. long. There are generally, however, three or 

 four pouches on each side of the oesophagus, and there may 

 be, as in a specimen from California, fifteen pouches altogether 

 (fig. 28). The vessels on the intestine are rather differently 

 arranged in this species (see fig. 26). 



The hairy -looking, dark brown, chlorogenous tissue present 

 in considerable quantity, especially on the ventral vessel in 

 A. marina (see Gamble and Asliworth, 1898, PL 2, fig, 5), is 

 present in A. cristata in the posterior half of the gill region, 

 forming small tufts on the oblique muscle bands. In the 

 other three species it is either altogether absent or feebly 

 developed (PI. 26, fig. 54). 



The histological features of the various portions of the 



