32 AET. 1. 1. T.TTMA : HEXACTINELLTDA, TTT. 



a ]3olypliyletic character is not thereby given to it. As to 

 Gaulocalyx, the presence of aspidoplumicomes (F. E. Sch,, '97, 

 p. o49) — the same peculiar hexasters as those found in Herhoigia 

 and Saccocalyx — indicates its affinity with these highly organized 

 Corbitellinae and so suggests tliat it had an origin later than, 

 and independent of Leiicopsaeus and Ckaunoplectella. With 

 respect to Placopegma, should F. E. Schulze's ('95, p. Q5) 

 assumption of tlie presence of a basal anchoring tuft prove correct, 

 the genus must probably be regarded as derived from the Eu- 

 plectellime, and not from the Corbitellinœ as is the case with the 

 other genera. The barbed anchor-needles that were discovered 

 iu P. solutum have been assumed by F. E. Schulze (/. c.) to be 

 pentactinic, each of the four anchor-teeth being taken for a real 

 spicular ray ; l)ut this seems to me highly improbable. The 

 short transversely disposed axial filaments forming a part of the 

 central cross in the said needle (/. c, Taf. vi, Fig. !(>) are far 

 from extending into the anchor-teeth and appear much too 

 abortive to allow of these being interpreted as real rays, but they 

 are only of such a degree of development as we see in a diactin 

 or a monactin of a similar strength ; so that, I think, the anchor- 

 needle is essentially comparable to that of the Euplectellinœ, save 

 in this relatively unimportant respect that the central axial cross 

 is brought down into the inferior swollen end, instead of being 

 situated some distance above it. 



Under the above circumstances it is with a certain degree of 

 reserve that I place Placopegma, and Gaulocalyx also, although 

 with somewhat less care, under the Leucopsacid* together with 

 Leucoinacui^ and Ghaunoplectella. I think the family may be 

 made to stand on the strength of the two last mentioned genera 

 ï\lone, if it should become necessary to remove the other two 



