the Ocnus Ti'agosia, Grai/. 173 



of species contaiuinji; trichodragmata and makes extensive 

 use of tliis form of spicule as a guide to classification. It 

 is not necessary to criticize his conclusions in this place, 

 except in so far as they concern the genus Tragosia. He 

 did not, of course, know that Tragosia iufundihuliformis 

 contains trichodragmata, or he must have realized tliat his 

 new genus A.cidrfigtna was not required. 



The diagnosis of A.cidragmu may he qiiotcd in full ; it 

 runs as follows: — " Axinellidie typically of tliin lamellar 

 hahit, stipitate, with even surface. Skeleton composed of 

 primary lines of stylote raegascleres, traversing the sponge 

 in the direction of its growth, and of secondary lines (con- 

 necting-fibres ?) formed of oxea ; there is no special dermal 

 skeleton. The megascleres are of the two forms mentioned, 

 which are quite distinct in kind. The mieroscleres are tri- 

 chodragmata accompanied or not by single trichites.^' This 

 genus is proposed for Topsent's Axinella padina []896], 

 from the Gulf of Lyons, a species which is shown by the 

 discovery of trichodragmata in Tragosia infundibuliformis 

 to be closely related to, if not identical with, the latter. 



It is quite clear that Hallraanu's genus Axidrugma 

 should be abandoned in favour of Tragosia. The synonymy 

 of the other Axinelline genera with trichodragmata is too 

 difficult and complex a problem to be discussed in this place, 

 but the study of these forms will probably be found to 

 afi'ord strong support to the view that the " Axinellidte" 

 are merely a heterogeneous assemblage of lipochelous Des- 

 macidonidse \_cf. Dendy, 1921 a, b]. 



List of Literature referred to. 



18G6. BowEKBAXK, J. S. A Monograph of the British Spongiudie, 



vol. ii. 



1874. . A Monograph of the British Spongiada^, vol. iii. 



1876. Cabteh, H. .1. "descriptions and Figures of Deep-sea Sponges 



and their Spicules from the Atlantic Ocean, &c." (Ann. & 



Mag. Xat. Hist. ser. 4, vol. .wiii.) 

 1877. . " Arctic and Antarctic Sponges, &c." (Ann. & Mag. Nat. 



Ilist. ser. 4, vol. nx.) 

 1916. Dendy, A. "Some Factors of Evolution in Sponges." (.lourn. 



(^ueliett Microscopical Club, vol. xiii.) 

 1921a. . "The Tetraxonid Sponge-Spicule : a Study in Evolu- 

 tion."' (Acta Zoologica, vol. ii.) 

 1921 B. . " Rnport on the Signiatotetraxonida collected bv TI.M.S. 



' Sealark ' in the Indian Ocean." (Trans. Linn. Soc, Zool. 



vol. xviii. pt. I.) 

 1828. FlemixCt, J. A History of British Animals. 

 1867. Gray, J. E. "Notes on the An-angement of Sponges, with the 



Descriptions of some new Genera." (I'roc. Zool. Soc. 1867.) 



