144 THE SPONGES OF THE WEST-CENTRAL PACIFIC 



hand, de Laubenfels, 1930, page 27, described from California a species as 

 asodes, which has palmate isochelas as small as only 3 /x long. The single 

 filiform toxa found in eurypa at first appears to be foreign, but it is note- 

 worthy that Stevens, 1916, page 239, describes from Ireland a species as 

 Eurypon ditoxa which had both filiform and typical toxas. Most of the 

 species now in Dictyociona were originally described in Eurypon. Appar- 

 ently, it is characteristic of Dictyociona that some of the species may have 

 excessively small chelas, and others may have two types of toxa. 



The species name eurypa is altered from Eurypon and signifies the par- 

 tial resemblance of this sponge to those in the genus Eurypon. 



GENUS MICROCIONA Bowerbank 

 Micro ciona plinthina, new 



Text Figure No. 92 



This species is here represented by the following : 

 U.S.N.M. No. 22949, My No. M. 322, here designated as type, collected 

 June 24, 1949, by diver at Ailing-lap-lap Atoll in the northeast corner 

 of the lagoon near Jih Islet. The depth was 5 meters, and the substrate 

 was dead coral. 



This species is incrusting, less than 1 mm thick, and spreading indefi- 

 nitely in all directions. 



The endosome and ectosome color in life was brick red, and the con- 

 sistency was slimy. 



The surface is smooth and lipostomous. 



The skeleton consists of megascleres, chiefly erect, with heads close to 

 the substratum and their points towards the surface. These comprise smooth 

 styles, 7 /x by 210 /x, and smooth tylostyles, 2.5 ii by 240 /a. There are also 

 spicules of the echinating type ; these are acanthostyles 6 fx by 105 /x. These 

 types are all abundant, and so are all the types of microscleres. The latter 

 include raphides, 1 /x by 100 /x, exceedingly sharp pointed at each end. Typi- 

 cal toxas, 50 [x long; and typical palmate isochelas, 15 /x long, also occur. 



Text Figure No. 92. Spicules of Microciona plinthina, X 782. A : Style. B : Tylostyle ; 



the entire spicule is shown, but in two parts. C : Acanthostyle. D: Raphide. E: Toxa. 



F: Palmate isochela, front and side views. 



