HOLASCUS EDWARDSII. 21 



Holascus edwardsii, sp. nov. 

 Plate 18, figs. 15-26; Plate 19, figs. 1-24; Plate 20, figs. 1-20. 



Two somewhat fragmentary specimens and two separate root-tufts of this 

 species were trawled in the Milne Edwards Deep, off the coast of central Peru, 

 at Station 4672, on 21 November, 1904; Palominos Light House, N. E., 163 km. 

 (88 miles) ; 13° 11.6' S., 78° 18.3' W.; depth 5203 m. (2845 f.) ; they grew on fine, 

 green clay; the bottom-temperature was 35.2°. 



Shape and size. One of the two specimens is faii'ly large, the other small. 

 The large specimen (Plate 20, fig. 4) appears as a fairly straight, somewhat conic 

 tube about 180 mm. in length. Originally this tube probably had a circular 

 transverse section. Now it is flattened, one side touching the other. The tube 

 is about 90 mm. in circumference at the upper end, and attenuated below to a 

 circumference of about 50 mm. Its upper margin has a lacerated appearance, 

 and is not to be considered as the true termination, but as a line of fracture 

 along which the upper end of the- sponge has been torn off. Below, this tube 

 gradually passes into the root-tuft, the upper part of which appears as a compact 

 stalk, circular in transverse section and 15 mm. in diameter. This root-tuft is 

 about 100 nam. long, considerably and uniformly curved, slightly attenuated in 

 the middle, and spread out distally to form a somewhat irregular spicular mass. 



The wall of the tube is 4-5 mm. thick. Its outer dermal face (Plate 20, 

 fig. 4) is very rough and irregular, an appearance probably due, to some extent 

 at least, to the indifferent state of preservation of the sponge. The inner, gastral 

 face (Plate 20, fig. 3) is perforated by numerous more or less circular apertures. 

 Two kinds of such apertures, large and small ones, can be distinguished. The 

 large apertures are 1.5-2.3 mm. wide in the central part, half way up the tube. 

 Toward both the upper and the lower ends of the tube they become smaller. 

 These apertures are very regularly arranged in one spiral line, or in a succession of 

 ring-shaped transverse rows. Within the spiral (the rings) they are close to- 

 gether, separated by walls of tissue, usually only 0.5-1.5 ram. broad. The spiral 

 turns (rings) themselves are farther apart, separated from each other by zones 

 3-4.5 mm. broad. The small apertures are mostly circular, 0.3-0.4 mm. in 

 diameter, and scattered in considerable numbers between the large ones. 



The small specimen is similar but only 42 nun. long, and also destitute of 

 the upper end. Its tubular part is not collapsed, circular in transverse section, 

 and 6 mm. in diameter. The root-tuft is bent quite round so as to form a semi- 

 circle. 



