110 PANAMIC DEEP SEA ECHINI. 



Young specimens of 9 mm. carry spheridia on the second buccal plate 

 (PI. 43, fig. rS). Spheridia are usually found on the actinal coronal plates 

 in Fh. placenta; in an Asthenosoma pellnddiim of 34 mm. we find spheridia 

 on the ambulacral plates in process of passing over to the actinal system 

 (PI. 51, fig. 5). In addition, on the actinal surface nearly to the ambitus the 

 half plates all carry spheridia (PI. 51, fig. 7). In Asthenosoma coriacevm 

 spheridia are found nearly up to the ocular plate on the posterior zone of the 

 left posterior ambulacrum (PI. 52, fig. 1). 



Kamptosoma Mort. 



Kamptosoma Mortensen, The Danish " Ingolf " Expeditiou. Echinoidea, Part 1., p. 60, 1903. 



A few specimens of Echini collected by the " Challenger," were left 

 in Cambridge, and were not returned to Sir Wyville Thomson with the rest 

 of the collection, owing to my ill health and the death of Count Pourtales. 

 Among them was a specimen labelled "PA. tenue?'^ from Station 272.' 

 The peculiar features presented by this specimen led me to examine it 

 again. I soon discovered that it differed greatly from Phormosoma teiiue, 

 and that it, as well as F/i. astei'ias, should form a new genus of Echinothuriae. 

 I came to this conclusion in 1898, at the time I was writing the Preliminar}' 

 Report of the Echini of the "Albatross" Expedition of 1891; at that 

 time the sketch notes, which have since been drawn out carefully b}- Mr. 

 Westergren, were made (PI. 50). In 1903 Dr. Mortensen published the 

 results of an examination he made of another specimen of Pk. temte? from 

 the same locality, and called attention to the interesting structure of the 

 ambulacral system of Ph. tenue and of Ph. asterias,- and proposed for these 

 two species the genus Kamptosoma. 



Kamptosoma indistinctum A. Ag. 



Phormosoma tenue A. Ag. pars., "Challenger" Echinoidea, 1881, p. 91. 



Plate 50. 



In a specimen of 42 mm. in diameter, from "Challenger" Station 272, 

 the actinal system (PI. 50 fig. /), measured 9 mm. in diameter, and the 

 nbactinal system 12 mm. In no genus of Echinothuria? is the contrast 



» In 2600 fiUhonis. in Lat. :?° 48' S. and Loup. 152° .■>6' W., east of Maiden Isd. ; bott. temp. 1°C. 

 ^ " Challenger '' Station 299. On the way to Valparaiso from Juan Fernandez, in 2160 fathoms. 



