MONOGRAPH OF JAPANESE OPHIÜROIDEA. 31 



to form very solid interbrachial borders. The peristomial plates 

 are stout, without median groove, soldered with the oral frames 

 and oral plates. A single, very long dental plate is present at the 

 apex of each jaw. The adorai shields are very stout, divided into 

 inner and outer halves, so that there are four in each interradius, 

 closely set together. The radial shields are stout, composed of 

 several secondary plates, which are soldered together. The ventral 

 arm plates are large, often divided into two or three secondary 

 plates. The lateral arm plates are very small, those of the two 

 sides not meeting each other ; in the distal arm joints outside the 

 second bifurcation, they are projected ventrally in the form of 

 hanging rods, bearing two hook-shaped arm spines. The dorsal 

 arm plates are represented by three or four rows of nodule -like 

 secondary plates on either side of each proximal arm joint, two 

 rows being internal and the other one or two external. According 

 to Lyman, the genital shts in Euryale aspera penetrate directly 

 into the " peritoneal cavity," which communicates with the peri- 

 haemal canal, and the generative glands lie in the " peritoneal 

 cavity," the " genital bursa3 " being entirely absent. As far as I 

 can judge, Lyman seems to be mistaken in his interpretation of 

 the parts. In my opinion, his " peritoneal cavity " is not the 

 genuine peritoneal cavity but merely the genital bursa?, which are 

 in direct communication with the perihsemal canal and are very 

 spacious and provided with a very thin membrane ; and the genuine 

 peritoneal cavity is perfectly divided into five radial compartments, 

 which are entirely filled up by the folded generative glands. The 

 correctness of this interpretation of mine is proved by the fact 

 that, the generative glands do not lie in the " peritoneal cavity," 

 as Lyman thinks, but are separated from it by a thin but distinct 

 membrane and the brachial body cavity, which is the direct con- 



