44 HOLASCELLA EUONYX. 



Holascella euonyx, sp. nov. 

 Plate 24, figs. 10-17; Plate 25, figs. 1-24. 



A fragment of this species was trawled nearly under the equator in the 

 Eastern Pacific at Station 4742, on 15 February, 1905; in 0° 3.4' N., 117° 15.8' 

 W.; depth 4243 m. (2320 f.); it grew on very hght, fine, Globigerina ooze; the 

 bottom-temperature was 34.3°. 



It is characterized by possessing hemionychhexasters and onychhexactines 

 with very long terminal spines (end-claws). To this the name refers. 



Shape and size. The single fragment (Plate 25, fig. 17) is a very slightly 

 cylindrically curved plate which may have formed part of a wide tube. It is 

 51 mm. long, 15 mm. broad, and about 1.5 mm. thick. 



The colour in spirit is brown. 



The internal skeleton is composed of parallel bundles of spicule-rays, and of 

 loose spicules. Near the surface special superficial (dermal, gastral) hexactines 

 occur. The bundles are composed of stout principals, for the most part tetrac- 

 tine, and slender comitals likewise chiefly tetractine. The loose parenchymal 

 spicules consist of numerous large and a few small simple hexactines ; a few hemi- 

 onychhexasters ; numerous onychhexactines; numerous small discohexasters 

 with many end-rays; very few large hemidiscohexasters with few end-rays; 

 and numerous large discohexactines. The special superficial hexactines have a 

 differentiated distal ray. 



Besides these spicules numerous small hexactines with curved rays, a few 

 pinules, and a good many large amphidiscs have been observed both in the sec- 

 tions and the spicule-preparations. These spicules are in all probability foreign. 



The distal ray of the superficial (dermal, gastral) hexactines (Plate 25, figs. 

 14, 15, 21-24) is fairly straight, 235-270 n long and about 6-10 ^ thick at the 

 base. Towards the distal end it is thickened more or less, the end itself being 

 abruptly pointed. At its thickest point, which lies a short distance below the 

 end, the distal ray measures 9-16 yu in transverse diameter. The basal part of 

 the ray is smooth, the distal part covered with stout, very oblique spines 1-2 n 

 long. These spines are somewhat curved, concave to the axis of the ray, and 

 point towards its distal end. These distal rays consequently somewhat resemble 

 wheat-ears. The axial thread extends quite to the tip of the ray, its end is not 

 covered with sihca (Plate 25, figs. 22, 24). The proximal and the lateral rays 

 are curved, cylindroconic or conic, at the base about as thick as the basal part 

 of the distal ray, smooth in their proximal part, and covered with minute oblique 



