BY E. V. HALLMANN. 769 



the main skeleton is a renieroid or sub-renieroid reticulation of 

 small acanthostyli, and the only additional megascleres present 

 are smooth dermal styli or tylostyli belonging to the category 

 of auxiliary megascleres. 



Type, I. tuberosa Hentschel (9) ; the only species. 



The species for which this genus is proposed was referred by 

 its author to Lissodendoryx. Its exclusion from the latter 

 genus, however, is necessitated by the fact that its isochelse are 

 of the palmate type. In some other respects also it departs 

 from typical species of Lissodendoryx considerably. The spe- 

 cies is from Western Australia. 



Genus Tenacia 0. Schmidt. 



Definition. — Desmacidonidae in which the microscleres are 

 isochelae palmatae and toxa (the latter sometimes occurring in 

 dragmata), the main skeleton is a reticulation of well-developed 

 spiculo-spongin fibres echinated by acanthostyli, and the addi- 

 tional megascleres are smooth styli incompletely differentiated, 

 chiefly as regards size and situation, into three sorts occurring 

 respectively (i.) within the skeletal fibres, (ii.) interstitially 

 and subdermally, and (iii.) at the surface, directed perpendicu- 

 larly thereto, forming a dense dermal skeleton. 



Type, T. clathrata 0. Schmidt (18). 



The genus which in a former paper (6) I defined under the 

 name Rhaphidophlus Elders, I now consider to be more correctly 

 designated Tenacia 0. Schmidt. This is chiefly in view of the 

 fact that, whereas the identity of the latter has been definitely 

 established by the re-description of Tenacia clathrata furnished 

 by Wilson (25), the identity of the latter, — concerning which 

 we have no other information than is contained in Ehler's im- 

 perfect description of Rhaphidophlus cratitius (5), — is open to 

 question. The original publication of both generic names was 

 in the same year, 1870; and it is now difficult to ascertain 

 which has the absolute priority. The evidence, however, is in 

 favour of Tenacia, for, whilst Schmidt's paper was listed in the 

 Zoological Record for 1870, that of Ehlers received first men- 

 tion only in the Record for 1872. 



In spite of the rejection of the genus Rhaphidophlus by 

 certain authors, the right to recognition of Tenacia, as distinct 

 from Clathria, seems to me beyond dispute. In Clathria the 

 styli coring the skeletal fibres — the principal styli as they are 



