200 



HI'LLKTIN OF THK BURKAU (IK KISHKKI?:S. 



licvelcil iiKirniii uf till' li>\vor liall' n{ llio occliulcnt Ixirclcr lliere is an iiiflertcd sliar)> ridge. Toward 

 llie basal niartfin |1h> inner surl'aee is l(ins;itudinally i;r(Mived. 



The lery-uin (pi. vm. lii;. .">, (ii has a lona ])urpIo beak, nne-fourth the length of the whole plate. 

 The outer surl'aee is worn aliove. but the lower part is eaneellated b'ke the .sputum. The longitudinal 

 suleus is closed by infolding of its sides. The spur is long, rounded at the end, and situated at less 

 than its own width from the .scutal margin. On both sides the liasal margins .slope steeply to the .spur. 

 The interior is yellow, with a long purple spot in the middle. Artieular ridge .short, subereet and 

 ihiii. ,\ low, Hat, gently areuate rib runs from the spur to the apical beak, in which a tine cavity 

 l>enetrates from the apex of the |iuri)le spot. The depressor crests are few and not very strong. 



Ba-sal length of the walls 70 mm., height 75 nnn. Length of the scutum 31 mm., breadth 13. ,5 mm. 

 Length of tergum with s|inr '.VI nun., lireadth 12 mm. 



The mandible (fig. L'. n, left side) has four small teeth, the last adjacent to .several low obtuse denticle.s 

 at the lower end. The end of the maxilla is sigmoid, the upper half excavated, the lower convex. 

 It is armed with numerous stout and slender spines (fig. 2, c. right side). The first pair of cirri has 

 wiile rami like moth antenna', the posterior one three-fourths as long as the anterior, with greatly 

 jiroirnding segments, about 21' in number. The segments of tlu' anterior ramus are less ]m)truding 



'i^£: 



^'W^^^ 



-Hnliiuits (Kiuilit . A. .Srj.nnit rirnis; i', miOnlil)l'' 



and about :iO in nundier. The sei- I lirri dig. 2, .\ i lia\e siiliei|ual branches, and the protrusion of 



the .segments reaches its niaxinunn. The third cirri are longer, with nmch le.ss protruding segments. 

 The other cirri are much more slender, longer, with about 5 pairs of long spines on each joint. 



Type, no. 82403. I'. S. National Museum, from J/6(j//os.s station 4496, off Santa Cruz Light-House. 

 10 fathoms, fine gray .sand and rock bottom. 



The dense .structure of the walls of this sjiecies would almost entitle it to a jilace in Darwin's 

 section C of the genus lialunmt: but it is clearly related to li. jisillnciis of the Chilean coast by the 

 structure of the opercular i)lates and the cirri. It differs from B. psittaciis in the following respects: 



The sculpture of the opercular plates is tiidike, the longitudinal grooves being far deeper, and the 

 transverse ridges closer. The occludent margin of the scutum is bent inward, as well as the tergal 

 margin. The adductor ridge in the scutum stands free from the artieular ridge throughcjut, whereas in 

 B. psillacii.s the confluence of the two ridges forms a deep vaulted cavity above the depressor muscle 

 impression. The terga are much alike, but in />'. aquila there is no ridge along the carinal side of the 

 jiurijle sircak. such as occurs in B. psiltacus, and externally the hjngitudinal .sculpture is coarser and 

 the trans\'c'ise much iloser. There are numerous other dilfcrrnc( s in the walls, etc., but those given 

 above are amjily sullicii-nl for tin- discriminalinn of the s]iccic's. 



