MONOGRAPH OF JAPANESE OPHIUPvOIDEA. 65 



the general plan of the internal structure is similar to that of the 

 second type of Gorgonocephalus ; while in Astrodadus conlfcrns, the 

 plan is that of the third type, though the foldings of the gastral 

 pouches, as well as of the generative glands, arc more complex 

 and the layer of t!io glandular cells of the wall of the gastral 

 cavity is extraordinarily thick, so that the cavity itself is much 

 less spacious. In Asfroboa arctos, the internal structure is essen- 

 tially similar to that of the preceding, but there is often a fenestra 

 in each interradial septum between tlie two compartments of the 

 perihaemal canal plus genital bursa? on either side of an interradial 

 line, placing the two in communication with each other. In this 

 species, the inner side of the dorsal surface of the vertebrae is 

 strongly convex, and the outer side correspondingly concave. 



DÖDEKLEIN has divided the Gorgonocephalidce into two sub- 

 families according to the presence or absence of supplementary 

 plates in the spaces between the oral angles and the interbrachial 

 ventral surfaces. But his statement is in my opinion based on an 

 error, because my Astrotomince evidently have the supplementary 

 plates in question. In Astrothamnus echinacsus, the supplementary 

 plates in question are well developed, and the adorai shields are 

 separated by them from the interbrachial ventral surfaces. Besides, 

 there occurs a not very large supplementary plate among the 

 adorai shields and oral plates. The greater inner parts of the oral 

 plates markedly project ventrally. The oral skeleton is firmly 

 soldered together. The peristomial plates are entire, irregular in 

 shape, with convex dorsal surface. The oral frames are humped 

 dorsally near the outer ends, being much higher than the basal 

 vertebrae. Ludwig's ' first ventral arm plate ' is present at tlie 

 dorsal side of the distal end of each oral slit, being firmly solder- 

 ed with the oral frames. The second to sixth vertebrae are markedly 



