Miscellaneous. 395 



MISCELLANEOUS. 



A Classification of the Sponges. By Professor Sollas, D.Sc. 



The Porifera are a distinct phylum (Parazoa) of the animal 

 kingdom, divisible into two classes, namely : — 



I, Plethospongiae (irXiidos, a crowd). 

 II. Calcispongiae. 



The Plethospongia? may be subdivided into three orders : — 



i. Hexactinellidse. 



ii, Demospongise {dijfws, the common people), 

 iii. Mysospongiae. 



The Demospongise embrace the great majority of sponges, and 

 are divisible into two suborders, the Monaxonidae and Tetractinel- 

 lidae. The horny sponges may be added as a third suborder, the 

 Cerospongise ; but since they are probably of polyphyletic origin, 

 derived from different families of the Monaxonidae, it is open as an 

 alternative to distribute them among the families of that group. 



On the Pelagic Annelides of the Bay of Algiers. 

 By M. C. ViGuiER. 



From November 1884: to June 1885 I made daily investigations 

 at the entrance of the port of Algiers, for the purpose of studying 

 the pelagic fauna of the bay, and especially the Annelida. 



It is well known that the pelagic Annelida are divided into 

 several groups. Some, like the Heteronereids or Syllidise, without 

 alternate generations, only belong to the surface-fauna during the 

 short period of sexual activity. Others are pelagic during their 

 whole existence ; but this existence, which is very short, only 

 represents the same period of activity as in the preceding group ; they 

 are the sexual stolons of the Syllidiae with alternate generations, 

 the Folylostridii and Saccoreneides. Lastly, a third group includes 

 essentially pelagic creatures which have never been observed except 

 at the surface, and appear to be completely adapted for that mode of 

 life. From my observations all these organisms belong to the two 

 families Alciopise and Phyliodociae, for we can only regard as very 

 greatly modified Phyllodocise, on the one hand Tomopteris, and on 

 the other the curious Sagittelke. Considering the close affinity 

 which exists between the families Alciopise and Phyllodociae, which 

 were formerly confounded, one might be surprised that all the 

 animals composing the former being pelagic, there was only known 

 with certainty a single pelagic Phyllodocian, namely Hydrophanes 

 of Claparede. For good reasons I do not mention Lopadorhynchus, 

 Grube. Three other types of this family had, however, been seen. 



