No. 4] MORPHOLOGY OF Till'. ACT1. \OZOA. 159 



specific identity of Carlgren's form with //. pilatns seems 

 improbable; for, apart from the difference in the localities for 

 which the two have been obtained, the tentacles of the Chinese 

 form are longer apparently than those of H. pilatns, and to 

 judge from Carlgren's figures, the longitudinal musculature of 

 the tentacles is weaker and its mesogloeal processes coarser. 

 It seems preferable at present to regard them as distinct, and 

 since Carlgren, in his brief notice, has bestowed no specific 

 name on his Endocoelactis, I would suggest that it be named 

 Halcnrias Carlgrcni, as a slight recognition of the admirable 

 work which that author has accomplished on the morphology 

 of the Actiniaria. 



An examination of the arrangement of the tentacles of 

 H. pilatns with reference to the mesenteries was made in the 

 series of transverse sections and also by an examination of the 

 disk, and the results obtained were essentially the same as 

 Carlgren's. I was not able, however, to distinguish any dif- 

 ference in the position of the tentacles over the endocoels 

 bounded by the imperfect mesenteries, though on theoretical 

 grounds it is probable that some difference does exist, and, 

 furthermore, the study of sections seemed to indicate that the 

 tentacles over the directive endocoels were situated a little 

 nearer the mouth than were the others represented as being in 

 the same cycle in Fig. 2 ; an examination of the disk failed, 

 however, to confirm this appearance. 



As regards the systematic position of Halcnrias, a few re- 

 marks are in order. I at first ('93) assigned it to the family 

 Halcampidae, but later ('98) deemed it advisable to separate 

 it from that family and refer it to Hertwig's Antheomorphidae. 

 Carlgren in the mean time had established for his Endocoe- 

 lactis the family Endocoelactidae. There are apparently three 

 courses open for the disposal of the genus. It may be referred 

 to a family already existent, the definition of the family being 

 changed, if necessary, to accommodate it ; or it may be taken 

 as the type of a distinct family, as Carlgren has done ; or, 

 finally, it may be separated altogether from the Hexactiniae 

 and regarded as the type of a separate tribe. 



It seems to me that this last procedure is quite unnecessary, 



