272 Mr. H. J. Carter on two undescribed Sponges 



diiced to its minimum : Hyalonema &c. ; also the Calci- 

 spongiaj. 



Thus Chalina seriata, Bk., would come into the first divi- 

 sion, viz. that in which there is more sarcodal or horny than 

 siliceous development ; and Schmidt's Desmacidinae into the 

 third division, the reverse, viz. that in which there is more 

 spiculous than sarcodal or horny development. 



Make, however, the presence of the tricurvate or bow-like 

 spicule (for that is one of the spicules of Chalina seriata) 

 supreme, and the division based on the rigidity of the skeleton 

 breaks down altogether. 



Schmidt, in his ' Note to the Synonymy of Dr. Bowerbank's 

 Sponges ' (Z. c), takes the presence of the tricurvate or bow- 

 like spicule in Hymeniacidon Bucklandi, Bk., to be as acci- 

 dental as it is peculiar to the Desmacidin» 5 but I have shown 

 that its existence in this sponge is normal — or at all events 

 in Dercitus niger^ which is but a variety of it (Annals, Jan. 

 1871), =Pachastrellaj Sdt. ; and Schmidt himself places the 

 latter under his Ancorinidw^ that is, among the Pachytragian 

 sponges (op. cit.). 



So much for the value of a division based more on the 

 presence of certain forms of spicule than on the rigidity of the 

 skeleton, i. e., in this instance, on the tricurvate or bow- 

 like one. 



Now Chalina seriata and the Desmacidine Microciona 

 atrosanguinea are closely allied in form, habitat, and spicular 

 composition, but in the way that Ectyon S2)arsus is allied to 

 Acarnus innoynrnatus, where, as may be seen by the illustra- 

 tions, the rigidity of the skeleton in the former (PI. XVII. fig. 1) 

 depends as much on the keratified state of the sarcode as it 

 does in the latter (fig. 4) on the number and arrangement of 

 the large acuate spicules. Thus Microciona atrosanguinea 

 bears to Chalina seriata (better Seriatida, Gray, for it is not a 

 Chalina, if the latter be only tn^ro-spicular) the same relation 

 as Acarnus innominatus to Ectyon sparsus. 



The specimen of Ectyon sparsns in the British Museum was 

 evidently found on some strand, where it might have been 

 washed about for years before it was picked up for further 

 preservation — a way in which many foreign sponges are ob- 

 tained, as there is not much time for deliberate di-edging on the 

 survey of a perhaps distant and perilous shore ; and few be- 

 side naturalists care much for sponges beyond their intrinsic 

 value. 



Hence it is not surprising that the sm-face of this sponge, 

 after having been exposed, perhaps, for months or years on a 

 dry hot strand under a tropical sun, should present a greyish 



