122 



ZOOLOGICAL COLLECTIONS MADE DURING [Jan. 4, 



3. Small 

 Acuatc. 



Spincd 



Microoiona tuhcrosa, Bowk. 

 (Straits of Malacca.) 

 [ Spined all over. Length 

 \ -1077 mm. ; breadth -0079. 



Hymcdemnia folita. 

 gellau.) 



4. Equianchorate. 



' Very thinly 



sending out at intervals 

 echinated columns about 

 •34 mm. long. 

 ' Externally echinated by 

 small spined aouates ; sav- 

 code dark, not constantly 

 spicular. 

 Barcode Granular, reddish brown. 



Habit 



Dermis 



Spined all 

 •10135 

 •006334. 

 Same characters in both 

 incrusting ?, Incrusting. 



ovei'. 

 mm. : 



(Ma- 

 Length 

 breadth 



Echinating 

 columns buried in sarcode, 

 with the exception of ter- 

 minal spicule-points. 



Smooth, except at points of 

 projection of skeleton- 

 bundles ; slightly but con- 

 stantly spicular. 



Grranular, reddish brown. 



This appears to be its nearest described ally ; but it is placed 

 with Hymedesmia provisionally (in spite of its wanting the bihamate 

 spicule found in the type, H. setlandica) in preference to Myxilla 

 and Microciona, owing to its fundamental divergence in spiculation 

 from the type species of those genera. 



{Note. Any discrepancies between this account of M. tuberosa and 

 that given by Dr. Bowerbank in his description in Proc. Zool. Soc. 

 1875, p. 281, are justified by an examination of the type specimen. 

 The " somewhat complicated rete," said to be formed by the " ske- 

 leton-columns " {I. c.) appears to be not due to the sponge-skeleton, 

 but to an anastomosing mass of tubes formed probably by an arena- 

 ceous foraminifer; for the axis of the "columns" is, as a rule, not 

 spicular, but formed of minute grains of sand.) 



Trach^tedania ', n. gen. 



Sponge. Main skeleton composed of vertical inferiorly distinct 

 spiculo-fibres, terminating on surface in radiating brushes ; spicula 

 siliceous, united by a minimum of sarcode, lying parallel in fibre, of 

 three forms, viz. spined acuate, smooth acuate, terminally or sub- 

 terminally inflated cylindricals. Flesh-spicules siliceous, slender, 

 acerate. Sarcode pale-coloured. A basal lamina of spicules may 

 be present. 



This genus is based on the new species T. spinata. It differs from 

 all the known species of Tedania, Gray, in having three kinds of 

 skeleton-spicules, one of them being spined ; that genus, however, 

 seems to be the nearest genus at present defined. 



Trachytedania spinata, sp. n. (Plate X. fig. 10.) 



Incrusting, laminar. Surface level, glabrous ; under lens seen to 

 be minutely but thickly pitted. Colour yellowish white. Vents? 

 Pores ? Main skeleton a series of independent, approximately ver- 

 tical spiculo-fibres, about 3 to 6 spicules thick, rising from a basal 

 lamina of fine cylindrical spicules, and deflected laterally at surface, 

 there breaking up into a horizontal brush of somewhat radiating cylin- 



1 From Tpaxis, rough, in allusion to the spined basal spicules, and Tedania, 

 the name of the allied genus. 



