446 balaniDjE. 



would not have existed ovigerous fraena. I believe that 

 Anelasma and Xenobalanus are only analogically connected, 

 being no more related together by true affinity, than any 

 other two genera in the Lcpadidae and Balanidae. 



Sub-Family — Chthamalin^e. 



Shell with the rostrum having alee, but without radii : 

 rostro-lateral compartments without alee on either side: 

 parietes not porose. 



Mouth with the labrum bullate j palpi hardly touching 

 each other i third pair of cirri with the segments resembling 

 those of the fourth pair. 



The shell in this sub -family consists of four, six, or eight 

 compartments, with the addition, in Catophragmus, of several 

 whorls of supplemental compartments or scales, like those 

 forming the lower part of the capitulum in Pollicipes. The 

 rostrum has alae and no radii ; in shape and size it resembles 

 the carina. The rostro-lateral compartments are destitute of 

 aloe ; in all cases they overlap the adjoining compartments, 

 and have radii (when such are developed) on both sides. 

 In the genus, Pachylasma, however, the shell must be looked 

 to very young, in order to detect this normal structure, for soon 

 the true rostrum and rostro-lateral compartments become 

 blended together, making a compound rostrum, destitute, 

 as in the Balaninae, of alae, but furnished with radii. The 

 parietes are never porose, nor furnished with regular sym- 

 metrical ribs (representing the longitudinal parietal septa) 

 on their inner surfaces : sometimes, however, on the basal 

 internal edges, there are some irregular depending points. 

 In conformity with the simplicity of the parietes, the Radii 

 (which are seldom much developed) have likewise a simple 

 structure ; and often are merely formed by the simple lateral 

 growth of the parietes. The scuta and terga are articulated 

 together more deeply than is usual in the Balaninae ; and 

 the terga never have a long spur. 



