SOME JAPANESE ECHINODERMS. 



547 



not got the larva; sufficiently advanced in development to ascertain 

 whether or not they have a posterior cross-rod and postero-lateral 



processes. 



Of the Spatangoidea I have succeeded in getting ripe material 

 of only one species, BrissìiS Agassisi. Owing to the lateness of the 

 season when I got that material, the larvae did not reach their final 

 shape before I had to leave Japan. The postero-lateral rods, in which 

 the specific characters of Spatangoid-larvae are mainly found, have 

 not yet developed, so that the main character of this larva cannot be 

 given. The larva is, otherwise, of the form typical to Spatangoids. 

 The posterior process is rather short ; the rods of this process as well 

 as those of postoral and postero-dorsal processes are fenestrated in 

 their whole length. 



The Clypeastroidea yielded considerably better results. The larvae 

 of four species were reared, viz. Clypcaster japonicus, Mellita 

 japonicap Laganum decagonale and Lagamim fudsiyama. 



It may first be pointed out that these larvae all agree with those 

 of other Clypeastroids hitherto known in their skeletal structure 

 and general shape. There is no necessity for giving here further 

 details as regards the larvae of Clypcaster and Mellita. It may be 

 enough to say that in the Clypeaster-larva. the body skeleton is 

 quite smooth, with some branches at the lower end of the frame, 

 while the A/cllita-\a.rva. is very similar to that of the Mellita from the 

 Atlantic coast of North America. Laganum fudsiyama"^ affords 

 special interest in that it is a deep-water species ; I have got it from 

 depths of 200-80D meters. This is the first time that an Echino- 

 derm from the deeper water was studied as regards its development. 



1) This species is designated in Yos/riwara' 's Monograph of the Japanese Echinoidea 

 as Astrictypens Manni. Having no access to literature at present, I do not venture to say 

 that this is an error ; but anyhow I do not see why this should not be a Mei/ita, and if 

 I remember correctly, there is a Mellita japonica. 



2) Possibly this is really Lagjiimii pellucidum ; but I have not been able to decide 

 the point for want of literature. 



