BY E. P. KALLMANN. - 501 



stitially and also forming a dermal skeleton: and this peculiarity 

 may possibly prove to be associated with other distinctive 

 features of a character that would justify its exclusion from the 

 genus. According to Thiele(40), a partial differentiation of the 

 megascleres into several groups is exhibited in the case of B. 

 korenii also, but) apparently this occurs without relation to the 

 particular position which the spicules occupy, since he makes no 

 mention of the fact; and Lundbeck(30) further notes that in 

 H. capillifera there are present, in addition to the skeletal 

 spicules proper, smaller styli which are found only in the part 

 of the sponge nearest to the substratum, where they form a thin 

 layer. In all the remaining species of iJiemwa, so far as I am 

 aware, the megascleres are definitely of a single order (though 

 occasionally comprising both monactinal and diactinal forms). 



Hentschel(15) has recently referred to Biemna (under the name 

 B. aruensis) a species possessing neither sigmata nor tricho- 

 dragmata, but having as flesh-spicules small slender curved 

 tylostyli, which he terms " kommaformige Rhaphiden " and ap- 

 parently regards as homologous with the commata of species 

 like B. peachi. Inasmuch, however, as the remaining spicula- 

 tion consists of megascleres (of two distinct kinds) in the form 

 of (longer) subtylostyli and (very much shorter) tylostyli respect- 

 ively, and as, furthermore, the sponge is regularly dome-shaped 

 and prolongs itself upwards into a tubular process, it seems to 

 me practically certain that the species is one requiring to be 

 included in the family Polymastiidse. Unfortunately Hentschel 

 has neglected to investigate the structure of the skeleton, and 

 one therefore lacks the information necessary to decide whether 

 the species requires a new genus for its reception, or permits of 

 inclusion in the genus Polymastia itself. But, for the present, I 

 would recommend that the species be known as PoIymastia(l) 

 ariheiisis. 



Of species referable to Biemtta which have been assigned to 

 genera other than Biemna, Desmacella, Tylodesma, or Allanto- 

 phora, there is apparently only one, viz., Siymaxinella incrustans 

 l\irkpatrick(20). 



A few fragments of a sponge have been recorded from Christ- 



