THE SESSILE BARNACLES. 



253 



making a wide angle with the spur. The spur is long and tapers to 

 a narrow end. The scutal border is very narrowly inflexed. 



The compartments may be separated readily in some individuals, 

 but in others the sutures are calcified and the wall will break through 

 the parietes rather than part at the sutures. The sutural edges, in 

 individuals which part there, are flat and smooth without the irregu- 

 lar crenulations representing radii in T. s, squamosa. 



In this race the articular ridge of the scutum is longer than in T. s. 

 squamosa-, and not united above with the adductor ridge; the crests 

 at the base are much stronger, the teeth of the more broadly inflexed 

 occludent border are larger and less numerous, and the external sculp- 

 ture is more effaced. There are also differences in the terga and walls. 

 The color is toward purple instead of green. The opercular valves 

 are larger relative to the size of the walls than in T. s. squamosa. 



I have seen a good many specimens. It seems to be the prevalent 

 form of the species in Japan. Doctor Kriiger reports it (as var. 

 nigrescent} from Tokyo and Sagami Bays and the Pescadores. 



TETRACLITA SQUAMOSA RUFOTINCTA, new species. 



Plate 58, figs. 5 to Qa. 



Type. Cat. No. 48055, U.S.N.M., from Aden. 



Distribution. Gulf of Suez to Zanzibar. 



The surface is eroded, showing fine short ridges or raised lozenges ; 

 pink (hydrangea pink to pinkish vinaceous of Ridgway) ; sutures 

 often scarcely or not visible; sheath colored like the outside. Wall 

 very thick, Avith many rows of small pores. Diameter 30 to 44 mm. 



Scutum livid brown and whitish within, adductor ridge well de- 

 veloped, but low, and in the upper part it is low, close to and united 

 with the articular ridge by a callous partly filling the groove. In 

 the lower half of the inflected occludent margin there are 6 to 10 or 

 more short, oblique teeth. 



Tergum with the basocarinal angle very prominent, the basal mar- 

 gin nearly transverse to the adjacent margin of the spur. Scutal 

 margin only narrowly inflected. 



This race is readily recognized by the pale color of exterior and 

 sheath, the small pores, the shape of the tergum, and the numerous 

 " teeth " of the occludent border of the scutum. 



