114 



GEODIA AGASSIZII. 



One of the two specimens from Station 4228 is, like the one described by 

 Lambe, in some respects immature in character; all the others, although of 

 various sizes, are apparently adult. In the case where more than one adult 

 specimen was obtained at the same station, these are fairly identical in structure. 

 The adult specimens from different stations, on the other hand, differ more or 

 less, but although these differences are not inconsiderable, I have, for the reasons 

 given below, united all in one species and have refrained from further sub- 

 dividing this into subspecies, varieties, or forms. 



Shape and size. All the specimens have a more or less continuous surface 

 and arc massive and destitute of vestibular or praeoscular cavities. The greater 

 number are attached by a small base and are either quite regularly spherical 

 (Plate 26, figs. 16, 19, 20; Plate 34, fig. 17), oviform (Plate 26, figs. 17, 18), or 

 somewhat irregular (Plate 26, fig. 21). Some are more cushion shaped and 

 attached by an extended base. The largest specimen, which is a stout ovi- 

 form one (Plate 26, fig. 17), was obtained at Station 4193. It is 130 mm. long, 

 105 mm. broad, and 100 mm. high. Smaller, more or less regularly spherical 

 specimens, 20-55 mm. in diameter, were obtained at Stations 2886, 4228, and 

 4551. The smallest one of these, which is at the same time the smallest of all 

 the twenty-two, is the immature specimen above referred to. Two elongated 

 ones, measuring 68 X 35 X 35 mm. and 46 X 20 X 20 mm. respectively, were 

 trawled at Station 2886, and another elongated one, 47 X 32 X 30 mm., at 

 Station 2887. The specimens from Stations 2978, 3088, 3168, and 4199 are 

 broad-based, more or less cushion shaped, and not so regular in outline. The 

 largest of these was obtained at Station 4199. It measures 50 mm. in length, 

 46 mm. in breadth, and 34 mm. in height. The maximum diameter of the others 

 is 24-46 mm. The specimens from Station 4199 show a predilection for the 

 concave, inner side of tubular hexactinellid skeletons. One of them quite fills 

 such a tube, three quarters of the circumference of which is still present. The 

 immature specimen described by Lambe is smaller than any of these. It 

 measures only 12 by 10 mm. 



In all the specimens by far the greater part of the surface is free from pro- 

 jecting spicules and finely granular, or, as in the specimens from Station 4228, 

 nearly smooth. In some remnants of a spicule-fur have been observed. In 

 the large specimen from Station 4193 there are a few areas with projecting spic- 

 ules up to 16 mm. long and lying very obliquely to the surface. In the cushion- 

 shaped specimens from Stations 2978 and 4199 a well-developed spicule-fur, up to 

 9 mm. in height, is observed in sheltered places near the base of the sponge. 



