CHAETODERMA HA\YAIIEXSIS. 49 



DESCRIPTION OF SPECIES. 



Chaetoderma hawaiiensis, sp. nov. 



Two specimens of this species were dredged in the vicinity of Kauai Island. 

 The first came from the western end (Sta. 4130) at a depth of 283-309 fath.; 

 the second from the northern extremity, Mokuaeae Islet (Sta. 3992), at a depth 

 of 528 fath. 



The first specimen was found in a mass of polyps of Epizoanthus (Plate 2, 

 fig. 3) elevated at least a foot above the bottom, and densely matted together 

 in such a manner as to preclude the possibility of accidental lodgment. The 

 second individual was found by Dr. W. K. Fisher among the spines of a species 

 of starfish {Odinia pacifica Fisher) also in such a position that it could scarcely 

 be due to accidental shifting. There is no especial reason for considering this 

 species a parasitic form nor indeed a commensal, for the food in the alimentary 

 canal consisted of small quantities of plant spores, sponge spicules, and organic 

 debris such as is ordinarily found in those species that burrow in the ooze. It 

 seems more probable that it, like Chaetoderma nitidulum, as described by Wiren, 

 may leave its burrow to crawl about on the bottom, or as in the present case even 

 on the bodies of other animals. 



In its external features this species displays the usual characteristics of 

 other members of the family. The body including the globular and apparent!}' 

 non-retractile prothorax, itself about 2 mm. in length, is 12 mm. long. Imme- 

 diately behind the swollen part of the prothorax the diameter of the body is 0.65 

 mm., and this continues with little change through the anterior half of the ani- 

 mal. Beyond this point the calibre gradually increases to I3 mm. in the neigh- 

 borhood of the cloaca, beyond which a slight decrease occurs that continues to 

 the end of the body. In the other specimen the size of the prothorax is the same, 

 but the length of the metathorax (19 mm.; diameter 0.5 mm.) and the abdomen 

 (7 mm. ; diameter 1 mm.) is considerablj' greater and bears witness to the futility 

 of using the length index in the discrimination of some species. 



The color of both specimens is a slaty gray, though this is usually obscured 

 bj' an inorganic incrustation covering the body generally. In the region of the 

 metathorax the larger spines are completely hidden in a granular deposit that gives 

 this part of the animal a brick-red shade. The same substance, in one case black 

 in color, is present in several other species of Chaetodermatidae in mj' possession, 

 and may perhaps be an excretory product thrown out from the coelomoducts. 



