THE SESS1LR BARNACLES. 



121 



rather wide and doep iiotcli. Oci'liideiit margin inflexcd, a rather 

 deep crease under it for the adductor muscle. No pits or scars for 

 depressor muscles are visible. Length 4.5 mm. (pi. 75, iig. Ic; also 

 fig. 94). 



The tergum is extremely thiclc, narrow, with a rather shallow 

 articular furrow. There is a sort of short spur united Avith the basi- 

 scutal angle and projecting below it. The carinal lobe of the valve 

 appears pushed upward. Crests for the depressor muscle are rather 

 strong and irregular. 



The numerous specimens of this species have been in the collection 

 many years, and the body was entirely destroyed in those opened. 

 The uniform violet black color of the interior is unusual and char- 

 acteristic. Chthaniahis iniertcxtus Darwin, a Philippine species, 

 is purple Avithin, but other known species are lighter colored or 

 clouded with some dark shade on a lighter ground. 



CIITHAMALUS CIRRATUS Darwin. 



18r>4. CfithaiiKilus cin-alus Dakwin, Rlonojiraph, p. -IGl, pi. 18, figs, -ia, 4b. 

 1909. Chthamalus cirratus Darwin, Pilsbry, I'roc. U. S. Nut. Mus., vol. 37, 

 p. 71, fig. 2. 



Distribution. — Pescadores Islands, Peru, to the northern Chonos 

 Islands. 



The barnacle is either depressed-conic, 10 to 13 mm. in diameter, 

 corroded above, ribbed and crenate at the base, when not croAvded, 



Fig. 95. — Chthamalus ciueatus. San Loiiknzo I.sland, Peru, inside views of teugum 

 and scutum enlarged, and guoul' ou tukee entire animals, natural size. 



or when croAvded the Avails become vertical, and the orifice and the 

 opercular valves are large. There is also a smooth form. Accord- 

 ing to DarAvin, large specimens from Coquimbo and Valparaiso have 

 a height of 1 inch with a basal diameter of half as much. All of 

 those I have seen from Peru are depressed. The interior is usually 

 dull purplish (fig. 95). 



The opercular valves are corroded. The scutum has a 7o7if/, straiKjlij 

 projcctiiKj articular rib., Avhich has a long, nearly straight or some- 

 times convex slope to the deep articular furroAv, unlike any form 

 pf C. stellatns. The adductor muscle pit is deep. The lateral de- 



