316 BULLETIN 03, UNITED STATES NATIONAL MUSEUM. 



SPECIES OF THE WEST COAST OF NORTH AND SOUTH AMERICA. 



CHTHAMALUS DALLI, new species. 

 Plate 73, figs. 3, 3a, 36. 



Type. Cut. No. 48064, U.S.N.M. 



Locality. Unalaska, Alaska, growing together with Balanus cre- 

 ncttus on Balanus cariosus. Also Oyster Bay, Washington, on 

 Balanus ylandula. 



The barnacle is conic, with a small oblong orifice ; parietes having 

 few unequal ribs, more or less obliterated by the corrosion of the sur- 

 face; sutures simple. Where corroded the surface is pale gray; in 

 a narrow basal band, where the very thin cuticle remains, it is buff. 

 The interior is whitish, stained more or less with flesh or a livid 

 tint. Opcrcular valves similarly tinted. 



Greatest basal diameter of the type 6.2 mm., height 2.3 mm. 



The scutum (pi. 73, fig. 3) has a moderately developed but short 

 articular rib, extending about to the middle of the tergal margin 

 and tapering downward. Articular furrow is broad. The pit for 

 tho adductor muscle is very shallow. There is a long and strong 

 adductor ridge. Pit for the lateral depressor muscle is crossed by 

 several crests. 



The tergum is broad, its width about three- fourths of the length, 

 the basal margin strongly convex below, straightened in its carinal 

 half. Upper margin well arched. The articular ridge is not very 

 prominent, articular furrow narrow. Crests for the depressor muscle 

 are quite long. 



The labrum (fig. 93^) is set with small, rather irregular teeth. 



The mandibles, palpi, and maxilhe do not differ materially from 

 those of C. stcllatus from Naples. 



Cirrus i has rami of 7 and 6 segments, the posterior ramus about 

 three-fourths as long as the anterior. 



Cirrus ii has 6 and 5 segments, the anterior ramus longer by about 

 1-2- segments. There are no serrate spines. 



Cirrus iii has rami of 12 segments bearing four pairs of spines. 



Cirrus vi has rami of 20 segments, bearing five pairs of spines, 

 some of them having single short basal bristles. 



This is a small species, but as the specimens contained many eggs 

 they may be presumed to be full grown. It differs from C. stelltitus 

 and its varieties by the strong development of the adductor ridge of 

 the scutum. It is most nearly related to C. fissits, but differs by the 

 crests in the scutum for the lateral depressor muscle, the far stronger 

 adductor ridge, and by the different proportions of the valves; 

 in C. fissus the length of the tergal margin of the scutum is half of 

 the basal margin; in C. dalU it is two-thirds. 



