122 THE SPONGES OF THE WEST-CENTRAL PACIFIC 



This had a vertical measurement of more than 10 cm and a horizontal meas- 

 urement of about the same. 



The interior and exterior color in life was dull yellow, and the consistency- 

 was cheese-like. 



The surface is exactly as in the preceding species — divided by ramifying 

 pore canals into rounded islands about 7 to 10 mm in diameter. The pore 

 grooves are about 1 mm deep and often less than 1 mm wide. The sponge 

 appears to be lipostomous; the exhalant as well as inhalant openings must 

 be located in these valleys. 



The ectosome and endosome also resemble the preceding species. 



The skeleton consists of acanthoxeas, about 6 /x by 250 p in dimensions, 

 and smooth oxeas, 7 /* by 500 p to 10 p by 600 p in dimensions. The micro- 

 scleres are trichodragmas, about 60 p long. 



This species was first described as Alcyonium granulatum by Esper, 

 1830, page 71. The genus Myrmekioderma was established for it by Ehlers, 

 1870, page 28. Neither of these authors makes any mention of microscleres, 

 but it is considered likely that trichodragmas would be overlooked more easily 

 than the very striking spicule known as the tylote. Esper's specimens were 

 from the East Indies, and thus there is a high degree of probability that they 

 are the same species as this from Truk. However, in Esper's specimen (as 

 redescribed by Ehlers), whereas the acanthoxeas were about the same size 

 as the Truk specimen, the oxeas are mentioned as smaller instead of larger 

 in size. Therefore, it is possible that a new species should be erected for 

 Specimen No. M. 453. 



FAMILY MYXILLIDAE Hentschel 



GENUS HIATTROCHOTA de Laubenfels 



Hiattrochota ditrochota, new 



Text Figure No. 76 



This species is here represented by the following : 

 U.S.N.M. No. 23021, My No. M. 400, here designated as type, collected 

 July 30, 1949, by diver in northwest Ponape between the reef and the 

 shore. The depth was 5 meters, and the substrate was dead coral. This 

 species was very common in the waters near Ponape. 



The shape is ramose, often sprawling, with many anastomoses between 

 the branches. The latter are about 15 to 25 mm in cross-section. Instead of 

 being round, this cross-section is exceedingly irregular in outline. The ver- 

 tical measurement extends up to at least 50 cm. 



The color in life was black with a superficial film of yellowish green, 

 and the interior was the same color. Upon handling, a profuse exudate of 



