REPORT ON THE HEXACTINELLIDA. 329 



base, which may either have grown upon a solid body, or may have formed a flat ex[tan- 

 sion on somewhat loose clayey ground. 



The largest of the specimens, bought by Dr. Doderlein in Enoshima in a dried con- 

 dition, attains a height of 10 cm. On the outer extremity of the tubes a simple smootli- 

 margined oscular opening occurs. Through the dermal and gastral sieve-like skin the 

 canals, which are from 1 to 2 mm. in width, may be recognised. 



In the dictyonal framework, which has been isolated by maceration, the gastral 

 margins of the longitudinally disposed dictyonal plates project freely on the inner surface, 

 while an irregoilar network of beams with round openings from 1 to 2 mm. in diameter 

 extends over the exterior. 



The dermal skeleton is formed of strong pentacts, with numerous inequalities over 

 the entire surface. A round knob or peg represents the atrophied distal (sixth) ray. 

 The long proximal ray and the four tangentials generally terminate in sharp points. 

 Scopulse also occur, each provided with a moderately long, terminally rough and pointed 

 stalk, and Ijearing on the outer simple conical expanded extremity of the latter four 

 rough, slightly capitate or entirely unknobbed, parallel or slightly diverging, terminal 

 rays (PL XCIII. fig. 4). In some specimens numerous fine spicules, which run out to a 

 point at both ends, occur in groups close to the proximal ray of the pentacts, and 

 project somewhat above the skin. 



In the gastral skeleton, curiously enough, I have found no pentacts or hexacts, 

 although numerous scopulse similar to the dermal forms were present in the familiar 

 radial position (PL XCTII. figs. 2, 5). 



The loose parenchymalia consist of very thin and short uncinates (PL XCIII. fig. 3) of 

 simple, slender, or somewhat rough hexacts (PL XCIII.) and oxyhexasters, each of which 

 bears two diverging, short, and strong straight terminal rays on each of the moderately 

 long basal principals. 



2. Hexactinella lata, n. sp. (Pis. XCIV., XCV.). 



Dichotomously branched tubes, which tend to anastomose, varying from 1 to 4 cm. in 

 diameter, expanding superiorly in funnel-like form. They are also frequently crowded 

 together laterally, and appear to be pitted or swollen out here and there in an irregular 

 manner. The wall of the tube has a thickness of 2 to 2 "5 mm. Through it one can 

 clearly recognise the radial and also the generally longitudinal, frequently undulating or 

 meandering plates, with the intervening spaces, while on the inner sitrface only ii-re- 

 gular round spaces are to be observed through the gastral skin (PL XCIV. fig. 1). In 

 completely macerated specimens it may be seen that, in the parallel longitudinal radial 

 plates of the dictyonal framework, the longitudinal fibrous bands exhibit an external 



(ZOOL. CHALL. EXP. — PART LIII. — 1887.) Ggg 42 



