152 COE 



The proboscis now bends sharply on itself in ordinary states of con- 

 traction and ends in an oval chamber \vith small lumen and very 

 massive glandular walls (figs. 2-5, pc). The cells lining this chamber 

 are highly columnar, irregularly arranged in several layers, and are 

 thickly packed with secretions which have great affinity for ordinary 

 stains. Posterior chamber closely imbedded in the surrounding con- 

 nective tissue (figs. 4, 5), and this appears to be connected with the 

 muscular walls of esophagus. Its movements are doubtless to a great 

 extent dependent on the contractions of esophagus, which, as described 

 below, is converted into a sort of muscular pharynx. 



Body Walls. Outer epithelium as in other genera, and richly 

 provided with glands. 



Muscular layers of body wall consist of a thin, external circular or 

 oblique layer of muscles and an internal longitudinal layer (figs. 7, S), 

 somewhat thicker than the former, but yet thinner than in most related 

 genera. Lateral nerves occupy the usual places internal to longi- 

 tudinal muscular layer. In this species, however, they lie internal 

 also to the thick layer of submuscular glands (figs. 4, 7, 8), and 

 therefore nearer center of body than in other genera where these glands 

 are not so highly developed. 



There is very little body parenchyma, the intestine filling most of 

 the space internal to the glandular layer, except at the time when 

 genital products are developing. 



Cephalic Glands. Throughout the head the tissues are crowded 

 with cephalic glands. Those situated more anteriorly open mainly on 

 tip of snout (text-fig. 18; pi. xix, fig. 5, ), but farther back they 

 open directly outward on all sides of body. 



Back of brain they pass gradually into subimtscular glands which 

 extend as a distinct layer throughout entire body. The glandular 

 cells composing this layer open directly outward to the surface (figs. 

 4? 7* 8, sg) and are situated on the whole circumference of body im- 

 mediately internal to the longitudinal muscular layer. The glandular 

 layer is in most regions so massively developed that it exceeds in 

 thickness all other layers of body wall combined. The secretions of 

 these glands furnish the sticky mucus by means of which the worms 

 cling so tenaciously to the crab or to other objects. 



Alimentary Canal. The esophagus, which leaves the rhyncho- 

 daeum just in front of brain (pi. xix, fig. 5), passes beneath the ventral 

 commissure as a narrow tube lined with rather flat cells, as in other 

 genera. Just back of brain, however, it becomes enormously enlarged 

 with high, columnar, ciliated epithelium, richly provided with gland 



