REPORT ON THE ASTEROIDEA. 69 



at once distinguish the form, and may ultimately entitle it to be ranked as a distinct 

 species, are the greater number of supero-marginal plates, the narrowness of the rays, the 

 character of the spinulation of the actinal interradial areas, the absence of pedicellarise 

 alike on this area and on the abactinal area, and finally the character of the adambulacral 

 armature. The madreporiform body appears to be somewhat smaller. 



Locality. — Station 133. In the South Atlantic, west of the island of Tristan 

 daCunha. October 11, 1873. Lat. 35° 41' 0" S., long. 20° 55' 0" W. Depth 1900 

 fathoms. Globigerina ooze. Bottom temperature 35°'4 Fahr. ; surface temperature 58°"0 

 Fahr. 



2b. Dytaster exilis, var. carinata, nov. 



This variety is characterised by the high and strongly keeled rays — a feature further 

 emphasised by their narrowness. The paxillse upon the disk are comparatively large and 

 distinct, and composed of rather robust but low papilliform spinelets, whilst along the ray 

 the paxillse become extremely small, and seldom have more than three to five papillae in 

 each. There are very numerous valvate pedicellariae along the margin of the abactinal 

 area of the ray, and also some upon the disk. In the type-form there are no pedicellariaa 

 on the abactinal area. The actinal interradial areas have numerous very large well- 

 developed pedicellarise irregularly arranged ; the individual intermediate plates which 

 cover the area are quite indistinguishable, and they bear small skin-covered papilliform 

 granules. In the armature of the adambulacral plates the spines of the furrow series are 

 large and thick, compressed transversely ; those of the second series are rather wide apart, 

 not more than five or six being present ; they are dagger-shaped, compressed longitudinally, 

 and are nearly as long as the furrow series. External to them is a row, sometimes two, 

 of small papilliform spinelets or granules. The solitary enlarged spinelet in the second 

 series of spines on the adambulacral plates is confined quite to the tip of the ray, where 

 it is thick and stumpy. The madreporiform body is remarkably large, and with very 

 coarse paxillse upon it. There are forty-two or forty-three supero-marginal plates. The 

 measurements are E, = 98 mm. ; r = 16*5 mm. 



Young Phase. — A small example taken at the same station seems to me to belong with 

 little doubt to this form. The dimensions are E= 11 '5 mm. ; r = 375 mm. Its general 

 appearance at first glance is very different from that of the adult, its facies and propor- 

 tions resembling those of Astropecten. There is as yet no indication of the narrow carinate 

 rays of the adult. There are eleven supero-marginal plates between the median interradial 

 line and the terminal plate. These extend well upon the abactinal surface, their breadth 

 being equal to, or even slightly greater than, their length, and they form a well-defined 

 border to the abactinal surface as seen from above, the breadth a little beyond the middle 

 of the ray being nearly as great as that of the intermediate paxillar area. The margins 

 of the ray are well rounded. The surface of the plates is covered with small, rather widely 



