Report on the zoological collections made in the Indo-Pacific Ocean ...

SPONGTIDA. 419DESMACIDINID^ (Schmidt, 1870).If all those sponges which contain hooked or bow-like fleshspiculeswere, in accordance with Vosmaer's views, as expressedin his vei'y useful llevision (Notes lioy. Mus, Netherl. ii. p, 99),included in this family, it would not only be the largest, in all probability,of the families of Siliceous S])onges, but it would leavesome of the remaining ones mere skeletons. Judged by the factsDOW known, the boundary region between the Desmacidinidae andChalinida? is now narrow, but not in reality so narrow as it wouldbe if the above definition is insisted on. Whatever may be theaffinities of Homoeodicti/a, with its anchorate flesh- spicules (referredby Mr. Carter to the Chalinidae), those of Toxoclialhia, mihi (seeChalinidfe, supra), are undoubtedly with that group ;yet it hasa bow-like flesh-spicule in conjunction with a Chalinid acerateskeleton-spicule, horny fibre, and digitate habit. Until the homologiesof the fiesh-spicules are better understood than they are atpresent, I believe that cases such as those just mentioned willhave to be considered separately on their individual merits as theyarise, having special regard to the direction in which the greaterassemblage of affinities point. It seems probable that this familywill only prove a fresh illustration of the maxim " Natura nonfacit saltum." Besides To.vochalina I here exclude from the familythose genera (e. g. C'lathria, Acarnns, Ecliinonema) in which anyof the spicules project laterally from the fibre ; such forms as theseseem to pass by gradations {Echinodictyum, Raspailia) almost intoAxineUa and PhaccUla, by losing, in the first case, the fieshspicules,and in the second {Axinclla &c.) the spined echinatingcylindricals. RMzocludina, on the other hand, seems linked to thefamily by its occasionally horny fibres, and by its ally Oceanapiawith its bihamate flesh-spicule ;and I have ranged it (although onlyprovisionally) here as a degraded Desmacidine. It probably owesits peculiar form to its mud-loving habits. Two new generic types,Gelliodes and lotrochnfa, are described below.RHIZOCHALINA.Schmidt, Atl. Geb. p. 3o.Phloeodictyon, Carter, Ann. 8f Mag. Nat. Hist. 1882, x. p. 122.This form is so aberrant in itscoarser anatomy that I think therecan be little doubt that Carter has done right {I. c.) in making it the typeof a distinct group, although we have as yet no satisfactory informationabout the arrangement and structure of the soft parts. Although Ican see no sufficient reason why the name Oceanapia, Norman, shouldgive way to the above names for such species as Desmacidon jeffrcysi,Bowerbank, whose spicnlation includes a bihamate, yet it seemsnot undesirable to retain the older of the two for those which havesimply an acerate spicule. With regard to the question of svste-2e2