562 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.39. 



Recent consideration of this form in connection with the present 

 collection led me to suspect that it was related to Antedon diomedese, 

 which I described from southern Japan and subsequently made the 

 type of the genus Perometra. Now Perometra belongs to a subfamily 

 of Antedonidse, all the species of which are remarkable for their 

 deficient pinnulation; in Perometra diomedese the first inner pinnule, 

 Po (the "pinnule on the third brachial") is always absent. Carpen- 

 ter saj^s nothing about the absence of any pinnules in Antedon 

 pusilla, but as he had overlooked the absence of P^ in describing his 

 Antedon 'perspinosa, I thought that perhaps a similar oversight had 

 occurred here. I therefore wrote to Professor Bell asking him to 

 investigate the point for me. With his usual kindness he has done 

 this, and he writes, "I have, as you requested, made an examination 

 of the type of Carpenter's Antedon pusilla and, so far as I can see, 

 there is no pinnule on the third brachial."'^ 



As in all other ways Antedon pusilla shows a general agreement 

 with A. diomedex, the type of the genus Perometra, it must also be 

 placed in that genus. 



Professor Bell adds that the type of Antedon pusilla is obviously 

 immature and regrets that it was described as a new species. I agree 

 with him and share his regret in regard to the species, though it is of 

 considerable interest to know that the genus Perometra occurs in the 

 Ki Islands. 



Plenty of material of Perometra diomedese is available, showing all 

 stages, from the very young to the adult; but the true status of P. 

 pusilla can not be ascertained until more specimens have been 

 secured. 



SvilDfamily ZEISTOIHETRIISr^. i 



Genus PSATHYROMETRA. 



PSATHYROMETRA PARVA, new species. 



Nearest to P. mira; the centrodorsal is as high as in that species, 

 but is much narrower basally (4 mm. in length by 3.2 mm. broad 

 at the base), so that it is considerably more pointed; the cirrus 

 sockets are in two converging columns in each radial area, two or 

 three to a column; there is no cirrus sockets between the proximal 

 ends of the two columns as in P. mira, but sometimes one of the | 

 proximal cirrus sockets of a column may be displaced more or less 

 inwardly; the bare interradial areas are as broad as in P. mira, but 

 somewhat less concave. The calyx and arms resemble, in so far as 

 they are preserved, those of P. mira. 



Type.— Cat. No. 27508, U.S.N.M., from station 5284. 



o Since the above was written I have personally examined the type of this species 

 in London, and I find it to be undoubtedly referable to Perometra, though the first 

 inner pinnule is present in all cases. 



