228 



The surface is encrusted with several other sponges, and 

 infested with embedded barnacles opening at the surface. 



Ihe most characteristic feature of the new species is the cali- 

 culate shape. The spiculation closely resembles that of Facha- 

 strella monilifcra Schmidt, but the megascleres of the former are 

 considerably larger than those of the latter. P. abyssi OS- is here 

 regarded as synonym of P. monilifera, O.S., as pointed out by 

 iopsent [12], p. 380- 



Pachastrella isorrhopa, sp. n. 

 Plates II and III, fig. 5. 



Sponge massive; pores and oscules not apparent; colour brown; 

 arrangement of skeleton as in preceding species- 



Spicules. AIegascler;es.- — Oxea, 3100 X 31 ,", straight or 

 curved. 



Amphityles (Fig. 5a) 480 X 10 /<, smooth, curved; head 25 

 X 10.5, long oval; neck 5 ^tt ; common in one specimen (A), rare 

 in a second specimen (Bj. 



Strongyles (Fig. 5b) 330 X 5-5 ", smooth^ straight; not found 

 in A, not uncommon in B. 



Smooth curved oxea (? foreign) 270 X 9-5- 



Caithrops, largest with each ray 590 X 62 /<. 



Microscleres.— Microstrongyles, 12 X 55 /', prolate-ellipsoid, 

 with granular surface. 



Microrhabds_, 11-33 /' "^ length by 2.7 /•. in breadth, curved and 

 crooked, closely and finely spined, not centro-tylote. 



.Vmphiasters 11 X 1 1 « > with 3-5 rough truncate rays. (There 

 is no room in the Plate for figures of all the spicules). 



Locality. — Cone Point, Natal, N.W. ^ W., distant 4 miles; 

 depth 34 fathoms. Bottom- — broken shells. 



The new species is represented by two specimens. Speci,men 

 A (the type), of triangular elevation, is 7 cm- in widtli, 25 cm. ni 

 thickness and 5 cm. in height ; the colour is dark brown. Speci- 

 men B forms a flattened cake-like mass, 8X5 cm. in area, and 

 4 cm- in height, the colour being paler than that of specimen A. 

 Both specimens are infested with barnacle-shells, which permeate 

 the whole mass of specimen B. 



This species differs but little from the preceding and from P. 

 inflnilifcra Schmidt, the chief distinguishing feature being the 

 curious amphityle spicules. 



Both the specimens^ A and B, are associated with a soft 

 Lithistid, which forms a flat cake-like crust on the upper surface 

 of B. In the case of specimen A, the Lithistid occurs as a nodule 

 deeply sunk in and incorporated with the Pachastrella, and com- 

 municating with the exterior by means of tubular vents passing 

 along a deep fissure in the Pachastrella. 



i(t6i>i')o-o^ equally balanced, ihe name being suggested by the 

 amphityle spicule?. 



