136 DISCOVERY REPORTS 



Spoladaster^ gen.nov. (Asteropidae) 



Characters. Those of the type species. 



If I understand correctly Mortensen's remarks concerning Culcita veneris Perrier, of 

 St Paul, this would probably belong also in Spoladaster. Its actinal interradial areas are 

 covered with fine spines which may occur, also, sporadically on brachyactis. 



Perknaster fuscus Sladen 

 (Fig. A, i-id, 2-2g, 4; Plate V, fig. i ; Plate VI, fig. i) 

 Perknaster fuscus Sladen, 1889, p. 551, pi. 62, fig. i, pi. 97, figs. 3, 4. 



A specimen collected by the Challenger at St. 149D, off Royal Sound, Kerguelen, was 

 forwarded by the authorities of the British Museum, Natural History. It carries the 

 Register Number 90.5.7.870 and measures R 34-35 mm., r 13 mm. It is therefore 

 slightly smaller than the type specimen which was taken at the same station and which 

 measures R 45 mm., ri4mm. The example under observation may reasonably be 

 considered typical of the species, a fact verified by Mr D. Dilwyn John. 



Considering the small size of Sladen's figures of the whole animal and the nature of the 

 subject, the artist was surprisingly successful. The small sacculate spinelets form a coarse 

 nap the exact texture of which is impossible to depict by a small scale line drawing. 



In Sladen's fig. 3, pi. 97, the spinelets appear to be rather more closely crowded than 

 in the smaller paratype; but the detailed figure of the abactinal spinelets (pi. 62, fig. i) 

 gives an excellent idea of these structures when covered by their heavy sheath of skin. 

 The actual spinelets are of course completely obscured by membrane. 



The abactinal spinelets are in groups of 3 or 4 on the larger plates, with only i or 2 on 

 smaller secondary plates. The fully developed spinelets (fig. A, i, la) are 0-54 or 

 0-55 mm. long, and the distal half is built up of thin, serrate laminae radiating from the 

 central axial portion in a rather characteristic manner. This gives the spinelets a clavate 

 contour, and when skin-covered they have as a consequence a coarser appearance than 

 in typical antarcticus of higher latitudes. The pedicel is distinctly low, as in antarcticus, 

 measuring o- 18-0-22 mm. (including thickness of plate), in sharp contrast to sladeiii in 

 which a comparable pedicel is 0-54 mm. high. In antarcticus, also, the spinelet has a 

 different form, lacking the prominent radiating laminae. 



After one has compared a series of different forms of Perknaster, the inferomarginal 

 plates oi fuscus seem fairly conspicuous. They are on the actinal face and form a definite 

 border to the actinal intermediate area and may be readily traced along the ray, where, 

 on the outer two-thirds they are adjacent to the adambulacral plates. They carry 5-8 

 spinelets which do not have so numerous nor such well-developed radiating flanges as 

 the normal abactinals (fig. A, ic). The form is rather like that of abactinal spinelets from 

 near tip of ray (fig. i d). 



An actinal spinelet from near mouth-plates (fig. i b) measures 0-65 mm. in length and 

 lacks the radiating flanges of the abactinal spinelets. The plates adjacent to adambula- 



^ EttoXols, -aSof, a leathern garment. 



