﻿SPONGES.-HALLiMAlNN. I^j 



Family ASTRAXINELLID.^, Dendy. 



Dendyi has suggested the advisability of instituting a ntw 

 fa. lily — Astraxinellidae — for the reception of certain Axinel- 

 lidcE which are distinguished by the possession of astrose 

 microscleres. The Astraxinellidae he would place in the divi- 

 sion Astromonaxonellida, whilst the Axinellidae in the 

 restricted sense would remain in the Sigmatomonaxonellida. 

 If we could learn all the facts concerning the phylogeny of the 

 Axinellidae it would no doubt be found that, whereas some 

 have been evolved from Desmacidonid and Haplosclerid 

 ancestors and some {? e.g., Trachycladus^) directly from more 

 primitive sigmatophorous forms, yet a considerable number 

 have developed along lines of descent which diverge from the 

 Astrotetraxonid stem. In a natural system of classification 

 the last-mentioned would be excluded from the Sigmatomon- 

 axellida, and they would probably require several families for 

 their reception. Unfortunately, it is impossible in the present 

 state of our knowledge to determine, in the majority of cases, 

 to which of the two primary Tetraxonid subdivisions a given 

 Axinellid genus belongs, and consequently no altogether 

 satisfactory bipartition of the family is to be expected without 

 much further enquiry. Nevertheless, there is much to be said 

 in favor of a removal forthwith from the Axinellidae of such 

 genera as afford sufficient evidence of their Astrotetraxonid 

 affinities ; and these might very well be placed provisionally 

 in a single family, irrespective of any question as to whether 

 their relationships are close or distant. On this understanding 

 I feel but slight hesitation in placing under the family Astrax- 

 inellidae the new genus Paracordyla, which possesses an Axin- 

 ellid type of skeletal structure and yet has microscleres in the 

 form of amphiasters. 



1 Dendy— Rept. Pearl Oyster Fisheries, Gulf of Manaar. with Kept. Mar. 



Biol. Ceylon, Part 3, 1905, p. 107. 



2 In this connection, I would suggest that a new family— Spirasigmidae 

 —be established to include Trachya oJobnsa- Carter (Ann. Mag. Nat. Hist., 

 5, xvii., 1886, p. 121), and its variety, rugosn (Ov. cit-, xviii. 1886, p. 457), 

 GelliHS acideatiis. Whitelegge (Sponges of Funafuti, Austr. Mus. Mem., 

 iii., 5, 1897, p. 326), and perhaps also the genus Tnichycladus. For the first- 

 mentioned of these species Topsent (Mem. Soc. Zool. France, vii.. 1894, 

 p. 8), has already proposed the genus Traclu/aelHufi; for the second I now 

 propose a new genus Spirasigina. In both of these genera the micro- 

 scleres resemble the sigmaspires of Trachycladus more closely than they 

 resemble ordinary sigmata, and the conformation of the skeleton is 

 strongly suggestive of their derivation from the Tetillidfe. Of these 

 species I have examined (only) sections which were prepared by Mr. 

 Whitelegge— those of T. (ilohnsa and its variety having been cut from 

 pieces of British Museum specimens, and that of the latter from its type- 

 specimen. If the former sections are correctly labelled— and I scarcely 

 doubt that they are- T. glohosa and T.<ilohom, var. rugosn are specifically 

 distinct. Both in Trachvaelliua and Spirasigma the skeleton has a radial 

 arrangement recalling that of the Donatiidae. In the former the large 

 diactinal spicules (oxea in the two known species) are accompanied by 

 sigmata only; in the latter (in which, in the single species, the large 



