E. A. Andreivs — Atiatoviy of the Spider Crab. Ill 



anterior edge of the pylorus downward and forward, and attached to 

 the apodenial framework of the first maxilla. Among the intrinsic 

 muscles on the lateral face, are four broad muscles («, n', n", n'", fig. 

 19) arising from the posterior lower edge of the cardiac region. The 

 upper two of these (w'", n") are attached to the super o-lateral ossicle 

 the next {)>') to the accessory cardiac ossicle, the lowest {?i) to the 

 calcified area on the side of the cardiac region. A pair of smaller 

 muscles connect the posterior part of the cardiac with the anterior 

 part of the pyloric region. From the latter, also, two muscles (o, o', 

 fig. 19) run upward on each side to the middle pyloric sac. 



The oesophagus is connected with the endostoma by two muscles 

 (l, I' fig. 19), on each side, one above and one below the commissure, 

 and by a pair from the anterior face («, figs. 19, 20). From the 

 posterior face a pair of muscles {b) pass backward and outward to the 

 points of attachment of the large mandibular abductors. The in- 

 trinsic muscles of the oesophagus may bring its walls in contact with 

 one another, and valvular folds at the opening of the cardiac region 

 act, in addition, to prevent the contents of the stomach from passing 

 into the oesophagus. 



The two ducts of the so-called 'liver' (I, fig. 1) enter the pylorus 

 at its extreme lower posterior end (A, fig. 19). They divide into 

 large branches Avith delicate walls at a short distance from their com- 

 mon opening ; and the numerous branches ramify throughout the 

 entire cephalotliorax and basal portion of the abolomen, receiving the 

 secretions of innumerable small, yellow, tubular sacs which make 

 up the mass of the liver. The liver thus occupies all the spaces left 

 between the other viscera and extends even a short distance into 

 the apodemal cells. 



The muscular wall of the stomach is continued posteriorly as the 

 wall of the intestine (i, fig. 19). The latter viscus is a tubular organ 

 extending back from the pylorus to the anus (an), which is on the 

 ventral face of the telson, or seventh abdominal segment, without 

 convolutions ; but it is not entirely straight, bending down under 

 the heart and then rising at the posterior part of the thorax on one 

 side of the median line, and in the reflexed abdomen necessarily run- 

 ning forward. 



The chitinous integument is continued inward at the anus as a 

 delicate cuticle lining the intestine as far as into about the fourth 

 abdominal segment where it terminates in a valvular arrangement 

 formed by five thickened ridges. Corresponding to this valve 

 there is a raised muscular ring (s) about the wall of the intestine 



