THE SPONGES OF THE WEST-CENTRAL PACIFIC 151 



=**i A 





r^ B 



Text Figure No. 98. Spicules of Desmacella lampra, X 782. A: Tylostyle ; the entire 

 spicule shows, but in two parts. B: Two of the sigmas. 



coral. This species was very common in the western portion of the 

 Truk lagoon, perhaps in other portions also. 



The shape is initially incrusting, but this species shows a tendency to 

 continue vertical growth so that many massive specimens were found. The 

 vertical measurement reached at least 10 cm. Horizontal measurements were 

 at least 10 by 20 cm. 



The ectosome and endosome color in life was fiery red-orange, and the 

 consistency was soft, almost a colloidal sol. 



The surface is very irregularly undulatory, but the pores and oscules 

 both close so rapidly that the lipostomous condition is achieved. 



The ectosome has only protoplasmic differentiation from the endosome, 

 and in both the fleshy structures predominate without any conspicuous reticu- 

 late skeleton. There are, however, vague ascending tracts of spicules. 



The skeleton consists of straight, smooth tylostyles, 2.5 ii by 250 /x. The 

 heads are elongated in the same direction as the long axis of the spicule. The 

 microscleres are sigmas, which may perhaps be regarded as of two size 

 ranges. Many are as small as 13 ju,; many others are between 30 /x and 33 fx 

 in chord measurement. 



No other species in Desmacella is extremely close to lampra, as most of 

 them have very large, thick spicules or dull colors or both. Most of them 

 also are persistently incrusting but show no tendency to rise up into massive 

 shape. 



The specific name is derived from the Greek word meaning "magnifi- 

 cent," especially "magnificent in color." 



GENUS MYCALE Gray 

 Mycale armata Thiele 



Text Figure No. 99 



This species is here represented by the f ollowing : 

 U.S.N.M. No. 22847, My No. M. 141, collected July 5, 1949, by diver at 

 Ebon Atoll from the Pearl Pool which is in the west portion of the 

 lagoon. The depth was 3 meters, and the substrate was dead coral. This 

 species was very common in this vicinity. 



