38 NATURAL SCIENCE. July, 



this system the distinction between axis and actine, first pointed out 

 by Sollas, played a considerable part. 



The outcome of the Expedition, in the case of the Sponges, was, 

 briefly put, to reveal to us the existence of a vast number of pre- 

 viously unknown forms, some of them of extreme interest, to extend 

 our knowledge of anatomy and histology throughout the group, to 

 render more natural our systems of classification, and to lay the 

 foundations of a knowledge of distribution, both geographical and 

 bathymetrical. No doubt there remains plenty of room for addition 

 and modification, but the more immediate need, in the study of 

 sponges, is for further knowledge of their embryology, and still more 



of their comparative physiology. 



W. J. Sollas. 



COELENTERA. 



Perhaps one of the most striking results of the " Challenger " 

 Expedition, so far as the coelenterates are concerned, was the over- 

 throw of the old group of the Tabulata. Doubt had, it is true, been 

 already thrown upon the value of the tabulae in corals as a 

 character for classification by the discovery made by Nelson and 

 Agassiz that the Milleporidse are hydroid and not anthozoan corals. 

 During the cruise of the " Challenger," Moseley was able to confirm 

 this result, and to give a first-rate description of the dimorphism 

 occurring in the family. The drawing which Moseley gave of the 

 expanded polypes of Millepora has been copied into nearly all the 

 standard works of zoology (PL vii., Figs, i, 2). But Moseley was able 

 to extend this discovery, and prove that all the genera belonging to the 

 family Stylasteridae are truly hydrocorallines. The volume of the 

 " Challenger " Report which deals with this family is perhaps more 

 full of valuable original results than any in the whole series. No 

 memoir that has been published before or since contains so accurate 

 and so detailed an account of the anatomy of any group of corals. It 

 is, and will remain for many years to come, the only standard work 

 on this family. 



A great deal more might be written upon this result alone of 

 Moseley's work, but reference must be made to the striking and 

 unexpected discovery that the Tabulate coral Heliopova was not a 

 Zoantharian, but an Alcyonarian. The relations of this genus to 

 several fossil forms, such as Syringopora, Favosites, Halysites, etc., were 

 pointed out by Moseley, and the result of his investigations and 

 suggestions has been the final abandonment of the Tabulata as a 

 natural group. 



Another important investigation of Moseley's, made during the 

 cruise of the " Challenger," and published in the Results, was the 

 description of the anatomy of the interesting reef alcyonarian 

 Sarcopliyton, and the discovery of a dimorphism of the polypes in this 

 genus similar in some respects to that which was known to occur in 



