16 



Dr. von Lendenfeld further states that the sponge investigated 

 and described by me [Stelospongus ßahelliformis, Carter) belongs to his 

 genus )ìThorectmi, which makes its appearance as »n. gen.« for the first 

 time in ISSS, in the «Descriptive Catalogue of the Sponges in the 

 Australian Museum, Sydney«. We must regard this statement with a 

 good deal of caution when we consider the fact that the first example 

 of Thorecta described by the author (1. c.) is ))Thorecfa exemplum n. sp.«; 

 while the third is mThorecta exemplum var. secunda^ Hyatt«, under which 

 latter appears y)Spoiigelia rectilinea var. te?iti{s, A. Hyatt«, as a syno- 

 nym! I must decline to place any great reliance on the nomenclature 

 of an author who so persistently violates the accepted laws of priority. 



The second communication to which I referred at the commence- 

 ment of this article is by Dr. N. Poléjaeff, on Korotnetvia desiderata 

 and the phylogeny of the horny sponges. 



Dr. Poléjaeff tells us that we must abandon the idea of the 

 close relationship of the Keratosa with the Hotnorrhaphidae (especially 

 with the Chalininae) and consider the horny sponges as a palaeonto- 

 logically ancient group. He further maintains that the modern specu- 

 lations concerning the alleged polyphyletic origin of the Keratosa »alle 

 in der Luft schweben«, and that we must not artificially separate what 

 we can naturally unite. 



In the Report on the Challenger Monaxonida, and more recently 

 in a memoir on the West Indian Chalininae^ ^ I have firmly upheld 

 the opposite view to that of Dr. Poléjaeff, and I must still continue 

 to do 80. Unfortunately Dr. Poléjaeff does not state, in the com- 

 munication referred to, what he means by the term ))Keratosa((. If he 

 includes amongst the horny sponges only those forms which have ob- 

 viously not originated in comparatively recent times from true sili- 

 ceous sponges — and doul)tless there are such horny sponges — no 

 one will venture to question the truth of his views. If, on the other 

 hand, he includes amongst the horny sponges — as is usually done — 

 all those formes which are provided with a horny skeleton and destitute 

 of spicules, I think he will find few Zoologists to agree with him. 



In my paper last referred to, I have given what appear to me to 

 be conclusive arguments for believing that at any rate some sponges 

 with a well developed horny skeleton and entirely devoid of spicules, 

 have descended and are in process of descent, from s})iculc-bearing 

 Chaliniiiae. As only an abstract of this paper has as yet been published '^ 



' To be shortly published in the Transactions of the Zoolofjical Society of 

 liOndon. 



■^ Proceedings of tlie Zoolof^ical Society of I/ondon, 1887. 



