146 



BULLETIN 82, UNITED STATES NATIONAL MUSEUM. 



Whereas the extreme of slenderness in the oral pinnules is seen in the Ante- 

 donidse, in such genera as Trichomctra and Hathrometra (fig. 289, p. 221), the 

 maximum stoutness is found in Ilimerometra (figs. 270, p. 207, and 326, p. 227), 



The large species of the 

 genus Zygometra have oral 

 pinnules corresponding very 

 closely with those of the 

 species of Himerometra; but 

 the pinnules taper distally to 

 a more slender tip than is 

 usually found in that genus, 

 though such a tip occurs in 

 //. persica (fig. 272, p. 207) 

 and in H. bartschi. In f' t /- 

 toptometra the structure of 

 the proximal pinnules is very 

 similar to that of the proxi- 

 mal pinnules of the species of 

 < 'oma=teridse, though there 

 are no terminal combs. In 

 I: itilificr'nnts (figs. 190, p. 

 Ill; 191, p. 112; and part 1, 

 83. p. 136, and 84, p. 

 the oral pinnules are 

 very stout and sharply pris- 

 matic, recalling 1\ in certain 

 of the Thalassometrinse. 



In the genus Pontiometro 

 (fig. 277, p. 213), belonging 

 to the Mariametridse, P t is, 

 strictly speaking, the only 

 oral pinnule. It is nearly 

 eight times as long as the fol- 

 lowing pinnules on the same 

 side of the arm, very slender, 

 with about 50 segments. P, 

 is small, like P.,. 



The species of Colobo- 

 metridse collectively are in 

 their proximal pinnule struc- 

 ture strictly comparable to 



FIG. :_'08. LATERAL VIEW OF SPECIMEN OF PTEEOMETRA TKICHOFODA. * L 



the species or the Himero- 



metridae, Stephanometridse, and Mariametridse taken together, but the distal ends of 

 the segments in these pinnules are as a rule considerably more spinous than is the case 

 in these other families. In the species of Ollogomftridcs, Auttromftra, and A nalcido- 



