1 73 



I SAO IJIMA. 



free distal rays to that of an Italian poplar and giving the length of those 

 rays to be 100— 200//. — -Finally, among the Apiirocallisies brought back by 

 the " Siboga " from the Malayan seas, I have found specimens from certain 

 stations of hers to possess dermalia which are provided with distinctly 

 plumose distal rays, though not always agreeing in details of the appearance 

 of these. — In comparison with the specimens referred to above, the gene- 

 rality of the oriental form of A. bcatrix in the extended sense may be said 

 to stand markedly backward in the development of the distal ray of dermal 

 hexactins, — not only as a pinular ray simply, but also as regards its absolute 

 dimensions and the numerical proportion of the spicules provided with it in 

 relation to those in which it is entirely or nearly entirely suppressed. 



Scopules are present in the sponge wall but on the dermal side only, 

 either in a single form or in two forms. In the former case they 

 are all of a slim appearance and may well be called the leptoscopule ; in 

 the latter case there occcurs, besides the same leptoscopule, the second 

 form of a thicker and markedly different development, which may be 

 distinguished by calling it the pachyscopule. The constantly occurring 

 leptoscopule is of very variable length (f.i., 23C-320//, about 360/i, 400-464« 

 long in three different stocks). It is provided with usually 4 (sometimes 

 3 or 5) terminal branches (60-So/i, 75-90/*, 88-IOO,« long), which distinctly 

 diverge from the point of their origin and are gently outwardly bent, each 

 terminating with a knob-like or bulb-like swelling. The branches may be 

 somewhat geniculate in the basal parts as was given for "A. ramosus " by 

 F.E. Schulze in the Challenger Report, but that state is by no means of 

 general or common occurrence. The terminal swelling is invariably small 

 and is beset with whorls of minute barbs ; it never seems to develop into 

 the shape of a moderately large convex disc with toothed margin, as was 

 represented by Carter ('73, pi. xv. fig. 1) from a Portuguese specimen of "A. 

 bocagei" or by F.E. Schulze ('02, pl. xv. fig. 2 ; pi. xvi. fig. 4) from "A. 

 bcatrix " and "A. bocagei " from the Bay of Bengal. 



The pachyscopule, which in some specimens does not seem to occur 

 at all, though in some others may take the upper hand over the leptoscopule 



