82 THE VOYAGE OF H.M.S. CHALLENGEK. 



drioid reticulation of stylote spicules in which one can distinguish lines of fibre running 

 vertically towards the surface and there breaking up into projecting tufts of spicules. 



Spicules. — {a) Megasdera; of one kind only, viz., smooth, curved styli (PI. XIX. fig. 8), 

 gradually and sharply pointed, usual size about 0"35 by 0'0126 mm. (sometimes a little 

 larger). (b) Microsclera ; rather rare and of one kind only, viz., palmate isochelse 

 (PI. XIX. figs. 8a, 8&) ; with almost perfectly straight shaft, length about 0'03 mm. 



As regards external form this is one of the most remarkable sponges in the 

 collection, although its spiculation is extremely simple. Coming from a depth of 825 

 fathoms it affords a capital example of the manner in which deep-sea Monaxonida tend 

 to assume a definite and symmetrical external form. To judge from the number of 

 specimens brought home by the Challenger it would appear to be a very abundant species 

 at the place where it was found. From the fact that the main stem always terminates 

 in a lamella, and that the smallest lamella is always found at the bottom of the series, 

 we may pretty safely assume that growth takes place not from above but from below, and 

 that whUe the upper lamellae are gradually increasing in size, new small lameUse are 

 being one by one intercalated between the lowest previously existing one and the base. 

 The correctness of this view as to the mode of growth is practically proved by the exist- 

 ence in the smallest specimen of a very minute bud on the stem below the lowest of 

 the two lobes {vide PI. XVIII. fig. 3, «)• 



The only described sponge at all resembling this species in its remarkable external 

 form which we can recall is Foliolina peltata, Schmidt,^ but even here the resemblance is 

 not very great. 



Zoc«%.— Station 196, October 13, 1874; lat. 48° 30' 0" S., long. 126° 58' 30" E.; 

 east of Celebes Island ; depth, 825 fathoms ; bottom, hard ground ; bottom temperature, 

 36° "9. Thirteen specimens and some fragments. 



Esperiopsis challengeri, var. meangensis, Eidley and Dendy. 



1886. Esperiopsis cliallengm, var. meangensis, Eidley and Dendy, Ann. and Mag. Nat. Hist., 



ser. 5, vol. sviii. p. 341. 



We propose the above name for a fragment of a stem and two fragments of a lamella 

 which appear to have come from a specimen closely resembling the types of Esperiopsis 

 challengeri in external appearance and also in spiculation. The differences, so far as we can 

 at present judge, lie in the respective sizes of the spicules, and it is probable that when an 

 entire specimen is found they will prove to be sufficiently great to justify the erection of a 

 new species, when the varietal name given above will stand as a specific name. In favour of 

 the view of the close relationship of the two is the nearness of their respective localities. 



The spiculation of the variety in question is as follows : — (a) Megasdera ; smooth, 

 slightly curved styli, sharply pointed, varying a good deal in size, but much longer than 



' Spong. Atlant. Gebiet., p. 42, yA. iv. fig. 4. 



