REPORT ON THE HEXACTINELLIDA. 331 



i:^). Oxyhexasters, with long pointed terminal rays, rarely occur' (PI. XCIV. fig. 10). 

 The structure of the .soft parts does not essentially diifer from that observed in the Euretidae. 

 The few specimens of this form were trawled near the Little Ki island (Station 192, 

 lat. 5° 49' 15" S., long 132° 14' 15" E.), from a depth of 140 fathoms, and a blue 

 mud ground. 



3. Hexactinella ventilabrum, Carter (PI. XCVI.). 



The elegant simple cup represented on PI. XCVI. figs. 1, 2 (measuring 8 cm. in 

 height and 12'5 in greatest breadth), belongs to the collection of Hexactinellida which 

 was made by Dr. Doderlein in Enoshima, Japan. From a base about the size of a half- 

 crown, a strong, laterally-compressed stalk, 3 cm. in breadth and 1 cm. in thickness arises, 

 and this is continued into the somewhat bent body, which is compressed in the same 

 direction. This somewhat resembles a boat, and its cavity exhibits the openings of a 

 row of twelve branching canals of approximately ecjual width. The circular openings 

 measure from 2 to 4 mm. in diameter (PI. XCVI. fig. 2). 



Since the dermal and gastral skin in this dried specimen are only preserved here and 

 there in small remnants, the coarser structure of the dictyonal framework can be 

 recognised without further trouble. As in Hexactinella lata, the free outer margins of 

 the radially and longitudinally disposed, reticulate, fibrous plates (1 mm. in breadth), 

 distinctly project on the external dermal surface, while on the gastral surface of the cup 

 they are covered by the evenly expanded fibrous network. Instead, therefore, of clefts 

 I mm. in breadth, only round pores of equal breadth occur on the inner surface. The 

 meshes of the dictyonal network of fibres appear in many places to be almost regularly 

 square, although the longitudinal fibrous strands frequently run not quite parallel to 

 the bounding surface, but in arched bundles from the middle layer of the wall, and 

 diverge slightly towards the free outer and inner surfaces, so that their extremities 

 project freely on the surfaces. The beams of the fibrous network are irregularly, aud 

 more or less abundantly beset with low knobs. The dermal skeleton includes strong 

 pentacts like those in the skin of Hexactinella tuhulosa and Hexactinella lata, also 

 strong, four-toothed scopulse, and numerous fine spicules which are pointed at both ends. 

 Constituent elements of exactly the same character are to be found in the gastral skeleton. 



The parenchyma contains minute, rough rods, with pointed extremities, which corre- 

 spond somewhat to the uncinates. There are also oxyhexasters, with tolerably long, 

 diverging, terminal rays (PI. XCVI. fig. 8), further, discohexasters with long basal 

 ])rincipals, and numerous short (externally slightly convex) terminal rays (PI. XCVI. 

 fig. 5), and finally, discohexasters with short basal princij)als, and a few (three to 

 five) straight or S-shaped, tolerably long terminal rays (PI. XCVI. fig. 4). 



1 The spicules figured on PL XCIV. figs. 11, 12, seem to have come in accidentally, and were not found on careful 



re-examin:ition. 



