THE GEPHYllEA OF JAPAN. 37 



No hook or spine is present on the introvert. The tentacles 

 are filamentous and about 80 in number ; they are arranged in 

 16 rows, the oral ends of eacli set of two rows being joined by 

 a U-shaped ridge. 



The longitudinal muscles are divided into 15 broad bundles 

 which rarely anastomose with one another in the region of the 

 introvert. Of the four slender retractor muscles, the ventral 

 pair are the larger and spring I'rom the 2nd — 3rd longitudinal 

 muscles in the middle region of the body proper, while the 

 dorsal pair arise far more anteriorly from the fourth longitudinal 

 muscles on both sides (Fig. 65, vm and di/t). The dorsal vessel 

 [dv) is seen running along the whole posterior course of the 

 œsophagus and gives off very numerous short contractile villi. 

 The spindle-muscle {sm), fixed at both ends to the body-w^all, 

 gives off tW'O lateral branches (sm') at the very beginning of tlie 

 intestinal convolution. These branches end on the 6th longi- 

 tudinal muscles, nearly at the same level as the roots of the 

 dorsal retractor muscles {dm). There are, besides, two stout 

 fixing muscles {ßa) : one arises from the 4th longitudinal muscle, 

 close to the roots of the right retractor, and is attached to the 

 beginning of the rectum ; the otlier springs with two roots from 

 the first longitudinal muscle and is attached to the œsophagus 

 near the intestinal convolution. The segmental organs (so) are 

 small sacs of a deep reddish brown color; the external apertures 

 lie at the same level as the anus. The organs are entirely free 

 of a mesentery. On the dorsal lip of the funnel or the internal 

 opening, we constantly see two or more small processes, some 

 of which may subdivide into 2 or 3 branches. They seem to 

 be made up simply of the connective-tissue and of the external 

 peritoneal covering. I am at present unable to make any sug- 



