204 VERRILL 



they become true starfishes, large enough to care for themselves.' 

 This habit is usually associated with the lack of pedicellariae. It is 

 conducive to the formation of local varieties. The order may be 

 conveniently divided into two suborders : 



I. AVELATA Verrill. 

 II. VELATA Perrier. 



Suborder ALVELATA Verrill, nom. nov. 



This includes the more typical forms in which there is no dorsal, 

 tent-like marsupial chamber for the protection of the eggs and young. 

 The spines are either all free, or partially or wholly webbed together 

 into groups, as in Solasteridse, in which the groups of adambulacral 

 spines form transverse combs completely webbed together, and the 

 dorsal spinules are partially so. 



It includes the following families, represented on the Northwest 

 coast in shallow water : 



Family ECHINASTERID^. 

 Family SOLASTERID^. 

 Family MITHRODIID^. 

 Family ASTERINIDJE. 

 Also the following extralimital or deep-sea families, besides other 

 smaller groups : 



GANERIIDAl, Patagonian ; Antarctic. 

 ACANTHASTERID^, Tropical; Panamic. 

 PYTHONASTERJDjE, Deep Sea. 

 KORETHRASTERIDJE, Deep Sea. 

 MYXASTERID^, Deep Sea. 



Suborder VELATA Perrier. 



This group includes only the family Pterasteridae. It is remark- 

 able for having most of the spines webbed together in clusters and 

 for the remarkable development of a dorsal membrane, more or 

 less completely uniting the parapaxillse together, forming a dorsal 

 marsupial pouch or gonocodium in which the eggs and young are 

 carried. 



M. Perrier, in his later works, has separated the Pterasteridae as 

 an order (Velata). This may be overestimating the importance of 



' This is the case with the genera Henricia. Solaster, Pterasier, Hymenaster, 

 and others. 



