STAKFISHES OF THE PHILIPPINE SEAS. 241 



Sladen published no anatomical notes. In 190G I raised Nereidaster 

 to generic rank, including in it a species {Nereidaster bowersi) which 

 proves not to be congeneric with the type of Nereidaster. It is this 

 misconception of Nereidaster which I incorporated into a key to the 

 o-enera of Goniasteridae in the Asteroidea of the North Pacific, 1911f^ 

 \v- 170). 



I made a cursory examination of Rosaster several years ago and 

 thought I found rudimentary superambulacral plates. These are 

 not present. What I saw, on closer examination, proves to be curious 

 spiny outgrowths from the lower end of the ambulacral ossicles. 

 The arrangement of the gonads and the presence of abactinal 

 internal ossicles, similar to those of the species herein described, in 

 addition to external similarities, leave no doubt that Nereidaster and 

 Rosaster are the same. The external appearance of R. alexandri 

 is much like R. nannus, and even more like R. confinis (Koehler), 

 especialW with regard to the abactinal surface. 



The specimen of Rosaster alexandri (from off Barbados, 103 

 fathoms) which I examined has R only 16 mm., yet the gonads 

 are well enough developed to show the serial arrangement. There 

 are 4 of them in each series, the innermost being near the inter- 

 radial' septum and on the outer side of the row of plates next the 

 aclradial. The series follows this row to the margin (only a short 

 distance), and is then bent inward by the marginal plates. The 

 structure of the gonad resembles that of R. nannus and R. symhoUcus, 

 being a simple ovoid sac, or a small cluster of sacs. Sometimes these 

 show an incipient lobing, but it is slight. The other internal diag- 

 nostic feature is well developed. Two rows of abactinal plates on 

 either side of the median radial are provided with internal radiating 

 ossicles. The median radial plates may have 5 to 8 ossicles. Two 

 plates have the longitudinally directed ossicles (those connecting 

 consecutive plates of the same series) split in two, making with the 

 2 lateral ossicles of each side a total of 8. The other plates have 5 or 

 6. The ossicles are longer and slenderer than in R. nannus. The 

 intestinal coecum is divided into long fingerlike sacs, interradial in 

 position. The coelomic side of the ambulacral plates is raised into 

 a thin carina, from which arise numerous extremely delicate and 

 fairly long spiny projections, best developed on the proximal plates, 

 and on each plate at the lower end, although there are a variable 

 number along the whole length of the plate. At the lower end of 

 the plate they resemble a tuft of tiny calcareous hairs. In R. nannus 

 the plates are similarly produced into a thin knifelike edge on the 

 coelomic side, this edge separating consecutive ampullae, and show- 

 ing occasional short spinelike projections, or even appearing like a 

 saw, but never with the extraordinary delicate hairlike projections 



