SHALLOW-WATER STARFISHES 35 I 



VIII. PATAGONIAN, FUEGIAN, AND ANTARCTIC SHALLOW- 

 WATER STARFISHES CONTRASTED WITH THOSE OF 

 THE NORTH PACIFIC COAST.^ 



As already remarked, the Antarctic starfishes are abundant and 

 diversified, especially those of the subfamily Asteriinae. Most of the 

 latter, found in shallow water, belong to genera peculiar to the 

 southern hemisphere. 



One notable peculiarity is found in the large proportion of species 

 that carry and incubate their eggs and young, being brooders, or 

 pCBdophoric species. This peculiarity extends, also, to many of the 

 Antarctic Echinoidea, Ophiuroidea, and Holothurioidea. 



The genera of starfishes of the family Asteriidae, having this habit, 

 differ, also, in anatomical details and in the position of the genital 

 pores from those that produce minute eggs that develop into free- 

 swimming larvae, as is commonly the case with northern genera. 



Most of the pcedophoric Asteriidae carry their young in clusters 

 under and around the mouth, as in Leptasterias of the north, but 

 Stichaster nutrix Studer is described as carrying them in pouch-like 

 diverticula of the stomach, at least in part. 



This pcedophoric habit is not confined to shallow-water and littoral 

 species, for it has been observed in some species from considerable 

 depths, such as Anasterias helgicce Ludwig, and A. chirophora Lud- 

 wig, taken in 450 to 560 meters, in the Antarctic Ocean (see below). 

 In these species the young are attached together in large groups, like 

 clusters of grapes, by means of their adoral peduncles and a central 

 stalk. 



Although many of the Antarctic species agree with Leptasterias 

 of the north, in this habit of carrying their young, and some of them, 

 also, in general appearance, they do not appear to be nearly allied." 

 Most of them are regularly monacanthid, while Leptasterias is never 

 truly monacanthid. Some are diplacanthid, as in the case of Podas- 

 terias steineni and P. liitkenii (see below, p. 361). 



In the case of Leptychaster kerguelenensis Smith, the eggs and 

 young are carried on the back, under the protection of the projecting 

 spinules of the paxillae, which is more analogous to the method in 

 Pterasteridas, in which the supraspinal membrane gives additional 

 protection, and for a longer period of development. 



* In the following review I have omitted some imperfectly described forms 

 and all the abyssal species. 



* It may be safely assumed, I believe, that all species that carry their eggs 

 and young around the mouth, also have their genital pores on the ventral side, 

 and therefore cannot be congeneric with those that have them dorsal, as in 

 typical Asterias. 



