ASTEROIDEA 121 



Genus Pergamaster Koehler 

 Pergamaster Koehler, 1920, p. 237. Type P. tesselahis Koehler. 



Koehler has made the curious error of describing the peripheral granules of the 

 abactinal and marginal plates as small />/« to. He says, " Les plaques dorsales du disque, 

 qui sont absolument nues, sont plates, assez grandes et sont separees par des plaques 

 trespetites ordinairement disposees sur deux rangs. Des plaques semblables et toujours 

 de tres petite taille, separent les plaques marginales dorsales et ventrales successives, et 

 separent egalement chaque rangee I'une de I'autre." These, of course, are not secondary 

 plates as the description implies but the flat granules such as are found on the periphery 

 of abactinal, marginal, and sometimes actinal plates of several genera of Goniasteridae, 

 e.g. Iconaster, Astroceramiis, Lithosoma, Plinthaster, CaUiaster. 



Koehler compares Pergamaster with Plinthaster but its 2 or 3 coarse furrow spines 

 and subambulacral tubercle are reminiscent of Astroceramiis. It seems to me that 

 Lithosoma and Iconaster (especially its subgenus Glyphodiscus^) are also related, but more 

 distantly perhaps than Astroceramiis and Plinthaster. Pedicellariae aid in establishing 

 relationships but these are not present in Pergamaster. 



Pergamaster incertus (Bell) 



(Plate II, figs. I, 2) 



Pentagonaster incertus Bell, 1908, p. 9. 



? Pergamaster tessellatus Koehler, 1920, p. 238, pi. 49, figs. 5-17. 



St. 1872. East of Joinville Island, Antarctic Archipelago, 63° 29-6' S, 54° 03-1' W, 247 m., 

 I small specimen. 



The specimen measures R 13-5 mm., r 8 mm., br at interradius 8 mm. It differs 

 from the type of incertus in having the actinal plates surrounded by only a single series of 

 granules as in the smaller specimen of synaptorus. If the latter species shows this varia- 

 tion, probably due to age, it is likely that incertus does also. The specimen has been 

 identified as incertus because the radial abactinal plates extend to the terminal plate, and 

 the abactinal plates and granules are less plane than in synaptorus and thereby resemble 

 more nearly those of incertus. Superomarginals 6 or 7, furrow spines 2 or 3 ; the distal 

 granule of inner subambulacral series enlarged to a clavate tubercle thicker than furrow 

 spines and of about the same length. 



Mr D. Dilwyn John had made two photographs of the type oi incertus, of which R is 

 26-27 mm., and r 14 mm., and which are reproduced herewith. Bell's vague remarks in 

 lieu of a description, though perhaps technically sufficient to establish the species, are 

 quite valueless for purposes of identification. The photographs show that the furrow 

 spines are generally 2 and that the subambulacral tubercle is essentially as in the small 

 specimen listed above. The actinal interradial areas are completely covered with granules 

 as in the type of synaptorus. 



1 Fisher, 1919, p. 306; G. perierctus Fisher, loc. cit. pi. 79, fig. 4; pi. 81, fig. 3; pi. 83, figs. 2, 3; pi. 93, 

 figs. I, I a. 



