266 HYALONEMA (PRIONEMA) AZUERONE. 



Hyalonema (Prionema) azuerone, sp. nov. 

 Plate 56, fig. 1; Plate 57, figs. 1-23; Plate 58, figs. 1-22. 



One specimen of this species was trawled in the Eastern Pacific at Station 

 4621 on 21 October, 1904; 6° 36' N.,81° 44' W.; depth 1067 m. (581 f.); it grew 

 on a bottom of green mud and rock; the bottom-temperature was 40.5°. The 

 Station is off the southern coast of western Panama, southwest of the Azuero 

 Peninsula, to which the name refers. 



Shape and size. The specimen (Plate 56, fig. 1) appears as a soft and resilient 

 disc with irregular lacerated margin. It is 275 mm. long, 255 mm. broad, 15-25 

 mm. thick, and forms (probably the greater) part of a sponge which may have 

 been broad and low cup- or vase-shaped, perhaps similar to Hyalonema populi- 

 ferum F. E. Schulze.' Fragments of large stalk-spicules, and slight remnants of 

 a protuberance indicate that a stalk was present in the living sponge, which arose 

 from the face bearing the protuberance. This face must be considered as dermal. 



The sponge consists of a mass of curved lamellae, mostly 2-3 mm. thick, 

 and joined to form a labyrinthic structure with elongate cavities or canals, which 

 have a maximum width of 1 1 mm. 



The colour in spirit is reddish brown. 



General structure and canal-system. In those regions of the lower (dermal) 

 surface where the superficial parts are intact, broad, oval pores covered by a 

 fine network are observed. One of these pores (Plate 58, fig. 4) measures 3.8 

 by 3.4 mm. The network covering it consists of straight threads 30-40 ji thick. 

 The nodes are considerably thickened; the meshes are triangular or irregularly 

 square, and 30-120 ^ wide. The flagellate chambers are curved, irregular sac- 

 shaped, and 80-140 /x wide. They form groups surrounding efferent canals and 

 lie, within these groups, close together. The chamber-groups are attached to 

 and held in position by a network of threads, spread out between them and the 

 superficial membranes of the sponge-lamellae in which they lie. 



The skeleton. The intact parts of the superficial (dermal and gastral) 

 membranes are covered by a dense fur of pinules (Plate 58, figs. 3a, 10, 11). 

 Small patches of the same pinule-fur also occur at the thickened nodes of the nets 

 covering the afferent pores (Plate 58, fig. 4). Pinules are likewise met in the 

 walls of some at least of the canals (Plate 58, fig. lb). These canalar pinules are, 

 however, not nearly so densely crowded as the superficial ones. Rhabds extend 



' F. E. Schulze. Amerikanische Hexactinelliden, 1899, taf. 2, fig. 7. 



