2j8 ••ENDEAVOUR" SCIENTIFIC RESULTS. 



usually anastomose freely. The superficial lamella 

 present their edges to the exterior. The superficial "ce//- 

 apertures^'' are polygonal or slightly rounded, averaging 

 about 2 mm. in diameter. Main fibres with a pauci- 

 spicular core; connecting fibres usually vacant. Echin- 

 ating spicules {apparently) confined to the superficial 

 fibres. Auxiliary megascleres rather scarce. Mega- 

 scleres : — (f.) Principal styli, straight, with a sub-basal 

 ivaist or constriction^ usually slightly fusiform^ varying 

 in size in different specimens from "jo-g^ x 5 )i to go-120 

 X 8 p; (ii.) auxiliary strongyla, with a maximum length of 

 betiveen 1^0 and 160 //, ay^d a maximum diameter of 

 between 1.2 and 2 jt. Microscleres : — Isochelce palmitce, 

 rare {or absent ?). 



Reasons for regarding this species as distinct from Len- 

 denfeld's Plectispa macropora are indicated in the remarks on 

 the genus Plectispa. 



It is a low, generally profusely branched and shrubby sponge 

 with a much abbre\ iated stalk, the base of which often is 

 extended into a disc-like foot ; the first-formed branches some- 

 times take origin from the disc, and the sponge may then ap- 

 pear as if provided with several stalks. The basal portion 

 of the sponge, just as are the branches, is formed of reticulat- 

 ing lameilje. Branching takes place by dichotomy which, as a 

 rule, is rapidly repeated. The sponge, as growth proceeds, 

 typically assumes the form of a hemispherical cluster of short 

 freelv anastomosing branches ; occasionally, owing to a re- 

 duction of the tendency towards rapid branching, the branches 

 become more elongated, anastomosis is less frequent and the 

 sponge assumes a more erect and arborescent habit. The 

 largest of a considerable number of specimens measures 150 

 mm. in height and 200 x 130 mm. in transverse dimensions. 

 The longest unbranched branches met with in any specimen, 

 measured 75 mm. in length. (The species recorded as E. 

 macropora by Whitelegge in his report on the "Thetis" 

 sponges, in which the branches sometimes attain a length of 

 over 300 mm., and the sponge a height of 500 mm., is £. 

 carteri, R. and D.) 



The superficial lamellce do not, as a rule, stand quite per- 

 pendicularly to the general surface, but are directed somewhat 

 obliquely forwards, i.e., in the direction of growth of the 

 branches : their outer edges are usually somewhat jagged. 

 The superficial "cell apertures" are normally hexagonal, but 

 in some specimens, particularly when the branches are com- 

 pressed, they show a tendency to become elongated in the 

 direction of the branch-axis ; they average slightly less than 

 2 mm., and rarely exceed 2.5 mm., in diameter. 



