THE MOUNT DESERT REGION 87 



Halichondria genitrix (0. Schmidt) 



Lundbeck (1902, p. 18, pi. 9, fig. 2a-c). 



This species was taken once in Chandler Bay, on hard 

 bottom, in about 50 feet of water. 



Skeleton. Spicules are scattered with no noticeable ten- 

 dency to form fibers. 



Spicules. These are long, slender, gradually tapering, 

 slightly bent oxea which occur in two classes as to size. The 

 large oxea of one specimen range in size from .292 to .693 mm. 

 and the small oxea from .121 to .203 mm. In the other speci- 

 men the large and small oxea vary in size from .405 to .851 

 mm, and .131 to .219 mm,, respectively. Oxea of sizes inter- 

 mediate between the large and small ones are found, but these 

 are relatively scarce and it would appear that the existence 

 of the two classes is real. 



Geographical distribution. West Greenland (Lundbeck), 

 Mount Desert Region. 



Halichondria fibrosa (Fristedt) 



Lundbeck (1902, p. 20, pi. 9, fig. 3a-c). 



Of this species there are several large specimens whicb 

 somcAvhat resemble Halichondria genitrix in their mode of 

 growth and outward appearance. These were taken at Sta- 

 tion D 104, rock bottom, depth 90 feet, 30 miles off shore. 



Skeleton. The skeleton is rather more confused than reticu- 

 late, but, in addition to scattered spicules, there is a tendency 

 for the oxea to be roughly arranged into tracts. Lundbeck 

 states that in his specimens the skeleton consists of ''loose 

 and irregular, not sharply marked fibers, which form, at all 

 events, frequently, a very irregular and indistinct network." 



Spicules. These are slightly bent oxea which are abruptly 

 pointed and of almost equal thickness throughout the length 

 of the shaft of the spicule. These oxea fall into classes ; the 

 larger ones vary in length from .511 to .730 mm. and the 

 smaller ones from .109 to .182 mm. 



Remarks, Halichondria fibrosa is distinguished from Hali- 

 chondria genitrix by the presence of small closely packed oxea 

 perpendicular to the surface. 



