256 Bulletin Vanderbilt Marine Miiseum, Vol. VI 



Family: ECHINOMETRIDAE 



Genus: PARASALENIA A. Agassiz 



Parasalenia gratiosa A. Agassiz 



Plates 91 and 92 



Type: Prof. Agassiz's type was collected at Kingsmills and 

 Society Islands and is deposited in the Museum of Comparative 

 Zoology of Harvard University. 



Distribution : This exquisite small urchin has a wide distri- 

 bution in the littoral fauna of the Indo-Pacific, being reliably 

 known from the Red Sea (Mortensen) down to Zanzibar on the 

 east African coast, through the Indian Ocean, at the Chagos Archi- 

 pelago and Maldives and north to Japan, southward in the Gulf of 

 Siam, the New Hebrides, New Caledonia, the Dutch East Indies 

 (de Meijere), the Torres Straits and Queensland (Clark), and 

 eastward to the Paumotu Islands and Samoan Archipelago. 



Material examined: Four specimens, taken at Pago-Pago, 

 Samoa, September 2, 1931, by the "Alva." 



Technical description : One of the "Alva" specimens has 

 the long diameter 23 mm., and the short diameter 20 mm. The 

 test is elliptical in contour, wider than high. The largest of the 

 "Alva" specimens has the long diameter 23 mm., the short di- 

 ameter 20 mm. ; the general form of the test being like that of 

 Echinometra, except that the periproct is composed of only four 

 anal plates and is moderately large with the long diameter equal 

 to about one-third of that of the abactinal system. The abactinal 

 system is elevated. The ambulacral and interambulacral spaces 

 have the tubercles arranged in two vertical rows, those of the 

 ambulacral areas being closely crowded. The pores are arranged 

 in pairs, forming an irregular vertical series. The genital and 

 ocular plates are smooth ; the genital plates having one or more 

 well developed tubercles. The primaries are moderately long, 

 gradually tapered, the longest ones being equal to or slightly ex- 

 ceeding the long axis of the test. In life the coloration of these 

 spines is very distinctive, the primaries being very dark, purplish 

 black, with the milled ring of each primary pure white. The sec- 

 ondary spines are quite small and not very abundant. In the very 

 young specimens of this species the primaries are said to be more 

 reddish and more or less regularly banded. 



