REPORT ON THE HEXACTINELLIDA. 277 



reference to macerated specimens. Only one of tliese can I regard as sufficiently diagnosed 

 to permit of certain recognition, namely, the form lately described by Carter, and desig- 

 nated by him as Farrea occa, Bowcrlxank. 



1. Farrea occa (Bowcrbank) Carter (Pis. LXXL, LXXIL, LXXIII. ; PI. LXXVI. 

 figs. 1-3). 



Both the material of the Challenger Expedition and the collection of the 

 Hexactinellida brought by Dr. Doderlein from the Sagami Bay, Japan, include 

 numerous specimens of this species of Farrea. These are partly spirit specimens with 

 the tissue preserved, and partly dried forms. They exhibit considerable diflerences both 

 in size and form. 



It is unfortunate that not one of all the specimens is quite intact. The outermost 

 ends of the tubes are generally broken off for a greater or less distance. I hope, however, 

 that the representation given in PI. LXXII. fig. 1, of a macerated skeleton in lateral 

 aspect, and those in PI. LXXL figs, 1 and 2, from photographs of spirit specimens in lateral 

 and superior asjiect, will give a correct conception of the general habit of this sponge. 

 It is frequently richly branched, forming composite masses sometimes 12 cm. in height. 



The simple hollow stalk is attached by a flat expansion to a more or less compact 

 substratum, sometimes consisting merely of a crumbly mass of clay. This expanded 

 portion consists of an irregular tuberculate plate, which is closely appressed to the 

 substratum. In its centre it has a thickness of 0'3 mm. or more, but becomes gradually 

 thinner towards the irregularly frilled edge, forming a delicate smooth margin. On the 

 free upper surface of this compact basal plate there are usually some radially disposed 

 furrows, from 1 to 2 mm. in breadth, whicli sometimes divide externally into two or three 

 narrower branches. From the lumen of the round tubular stalk which rises from the 

 middle of the plate, a round excurrent aperture leads either through the plate itself 

 straight dowmwards, or just above the plate through the wall of the tube (PI. LXXII. fig. 2). 

 The stalk, which usually stands erect at right angles, has a diameter of 5 to 10 mm. and 

 an equaUj' short length. It passes immediately by division and gradual expansion into 

 the crowded anastomosing tube-work of the stock. The ultimate ends of the tubes form 

 thin-walled smooth margined cups projecting freely on the somewhat uniformly arched 

 convex surface of the whole complex. The dichotomous division of the single tubular 

 ends takes place in the following fashion. The cup-shaped expansion extends transversely, 

 usually at right angles to the last plane of bifurcation, the two long parallel margins 

 thus formed approach one another in the middle and fuse, so that the cup becomes 

 divided into two independent and diverging tubes (PI. LXXII. fig. 3). After a more or 

 less prolonged growth these again experience a dichotomous division of the same sort. 

 The length of the tubular portion seems to vary greatly in different stocks and also in the 



