246 HYALONEMA (LEPTONEMA) CAMPANULA. 



The pentactine pinules with long distal ray (Plate 81, figs. 12, 13, 16-18). 

 In these spicules the distal ray is 230-810 fx long, most frequently about 000 /x, 

 5-8 M thick at the base, and fairly straight or more or less, sometimes very con- 

 siderably, curved. It is conical and it ends in an exceedingly fine, thread-like, 

 spineless terminal cone. The spines of the distal ray are small, rather sparse, 

 and strongly inclined towards the tip of the ray. They attain their largest size 

 at a distance of a fifth to a quarter of the length of the whole ray from the centre 

 of the spicule, and here the distal ray, together with the spines, attains its maxi- 

 mum thickness of 9-18 n. The lateral rays are cylindroconical, abruptly pointed 

 or l)lunt, and spiny in their distal part. Their length is, roughly speaking, in 

 proportion to the length of the distal ray. In the pinules with a distal ray under 

 400 fi in length, the lateral rays are 43-52 ^ long; in those with a distal ray over 

 400 n in length, 50-80 ^ long. 



The basal dermal pentactine pinules with shorter distal ray (Plate 81, figs. 

 25, 26). In these spicules the distal ray is straight, conical, 100-165 ^ long, and 

 5-6 n thick at the base. It bears rather sparse spines and ends in a sharp- 

 pointed and rather slender terminal cone. Its maximum thickness, together witli 

 the spines, of 12-23 /i is usually situated a little above the middle of its length. 

 The lateral rays are cylindroconical, abruptly pointed or rounded at the end, 

 distally spined, and 37-58 ^ long. 



The diactine pinules (Plate 81, figs. 1, 2, 14). In these pinules the distal 

 ray is straight or curved, 0.73-1.2 mm. long, and 6-9 yu thick at. the base. It 

 bears rather sparse strongly inclined spines. The largest are 10-16 fi long, and 

 arise about a third of the length of the distal ray from the centrum of the spicule. 

 Here the distal ray, together with the spines, attains its maximal thickness 

 of 12-18 M- Distally and proximally the spines decrease in size. The slender 

 thread-like extreme tip and the basal part of the distal ray are free from spines. 

 The proximal ray is usually fairly straight and 450-750 ^ long. The lateral 

 rays are reduced to cylindrical, terminally rounded protuberances only 5-14 ^ 

 long (measured from the axis of the spicule). 



The pentactine megascleres (Plate 81, figs. 19, 20) have a straight proximal 

 ray sometimes 1 mm. and more long, and 7-45 ju thick at the base. The lateral 

 rays of the same spicule often differ very considerably in size. They are 230 /j 

 to 1 mm. long, straight, or somewhat curved, and slightly inclined towards the 

 proximal ray; the angle between them and the proximal ray is usually about 85°. 

 The lateral rays are generally conical and terminally rounded, rarely thickened 

 at the end (Plate 81, fig. 19). 



