REPORT ON THE HEXACTINELLIDA. 313 



and similar pointed rays are beset only with short lateral prongs. Besides these 

 hexacts, which form with one another a quadrate dermal lattice-work, the dermal 

 skeleton contains numerous scopulse with their four or five knobbed prongs at right 

 angles to the surface, while the long slender smooth stalk runs out to a point. 



In the case of the gastral skeleton unfortunately nothing certain could be discovered 

 in the small dried fragment at my disposal ; on the other hand, the loose parenchymalia 

 were well preserved in great numbers. There were numerous uncinates arranged at 

 right angles to the bounding surface, and therefore parallel to the radial prismatic canals. 

 The greatest breadth of these does not occur at the middle, but in their outer third part, 

 while the attenuated gastral extremity gradually runs out to a fine point. The thin 

 pointed barbs of the uncinates are tolerably densely apposed. The peculiar elongated 

 oxyhexasters, which have already been described, occur scattered irregularly and in great 

 numbers throughout the whole parenchyma. 



2. Aphrocallistes hocagei, Wright (PI. LXXXIII. ; PL LXXXIV. figs. 1-8). 



Both among the Hexactinellida of the Challenger Expedition and among the others 

 purchased by Dr. Doderlein in Enoshima, there are numerous representatives of this 

 form. Some of these are well preserved in alcohol. The fully developed typical form is 

 a tube gradually widening upwards, with numerous radial glove-finger-like swellings 

 on the lateral walls. The axis of the entire tube, which may attain a length of 20 cm. 

 or more, exhibits as a rule a slight curvature. The inferior extremity, which is firmly 

 attached to the substratum, has the form of a small cup, the wall of which shows diver- 

 ticulum-like swellings only a few mm. above the basal plate, which is from 3 to 5 mm. in 

 breadth. These are at first quite low, but further upwards they gradually increase in 

 length, and finally attain a length of 5 cm. or more. The breadth of these diverticula, 

 which always end blindly, measures on the under end of the tube in most cases only from 

 3 to 5 mm., but gradually increases in the middle and upper parts to a diameter varying 

 from 1 to 2 cm. Very frequently much elongated diverticula occur here and there at a 

 short distance above the base. These are bent obliquely downwards, reach the firm 

 substratum or some laterally adjacent solid body, and become supports for the entire 

 sponge (PI. LXXXIII. fig. 1). In many cases the diverticula are arranged in more or less 

 longitudinal rows, which in the inferior part of the entire tube are usually four in 

 number and arranged in a cruciate manner. Superiorly this arrangement becomes 

 indistinct or is no longer to be seen. A well-marked whorled disposition of the diverticula 

 I have not been able to observe ; on the other hand, I now and again saw certain varia- 

 tions from the normal conditions which are perhaps of importance as to the relation of 

 this form to the others which, though separated off as distinct species, are at the same 

 time closely related forms. On the one hand, cases are not unfrequent in which a lateral 



(ZOOL. CIIALL. EXP. — PART LIII. — 1887.) Ggg 40 



