138 THE SPONGES OF THE WEST-CENTRAL PACIFIC 



by 166 p to 7 p by 170 p. Loose in the flesh and at the surface are many 

 small smooth tylostyles, 3 p by 117 p in dimensions. The fibers are echinated 

 by acanthostyles, which are about 4 p by 64 p. The microscleres include pal- 

 mate isochelas 13 p long, and in this species they have shovels of rather pe- 

 culiar shape. In addition, there are very numerous microscleres which are 

 between toxas and raphides in shape. They are only slightly more than 1 p in 

 diameter and upwards of 115 p long. Some are nearly straight, and some 

 are twice or three times bent. The shape of a toxa is thereby approximated. 

 This type of microsclere is very distinctive of the species cratita. 



This sponge was first described as Spongia cratita by Esper, 1794 circa, 

 page 188, from the East Indies and designated as type of the genus Raphi- 

 dophlus by Ehlers, 1870, page 18. A discussion of the genus Thalysias by 

 de Laubenfels, 1936, page 104, may be taken as the first transfer of this 

 species (and of the genus Raphidophlus) to the earlier Thalysias. 



Thalysias frondifera (Bowerbank) de Laubenfels 



Text Figure No. 88 



This species is here represented by the following : 

 U.S.N.M. No. 23149, My No. M. 533, collected September 22, 1949, by 

 diver at Agana Bay on the northwest coast of Guam. The depth was 2 

 meters, and the substrate was dead coral. 



The shape is irregularly massive with lobes which are large in propor- 

 tion to the basal region. A maximum height of at least 17 cm was reached 

 in Guam. 



The color in life was orange, obscured by a considerable amount of 

 foreign debris which covered the surface. The endosome was definitely 

 paler than the exterior. The consistency was stiff and wood-like. 



The surface is multiple tuberculate, with smaller tubercles on larger ones 

 of all sizes. The pores and oscules could not be made out, partly because of 

 the extremely irregular surface. There were small holes here and there, 

 but it was impossible to be sure whether they were actual oscules, or acci- 

 dents, or perhaps merely deep grooves in the rough surface. 



The ectosome is characterized by a fairly large number of spicules, 

 erect, with their points outward ; and it was covered by a considerable amount 

 of debris. The interior is characterized by a fibro-reticulation, but one which 

 is very vague. In such cases it is not practical to cite diameters of fibers. 



The skeleton consists of three types of megasclere and two types of 

 microsclere. The spicules which core the fibers, or make up the masses of 

 spicules which predominate, are smooth styles, about 5 p by 145 p. Some 

 are at least 11 p thick, but such were broken so that their total length is not 

 known. Other spicules occur at the surface, and in the spaces between the 

 masses or bundles of styles. The latter are smooth tylostyles, 2 p by ISO p 



