1908.] NATURAL SCIENCES OF PHILADELPHIA. 107 



North Atlantic Group — Scilkelepas Segueiiza: 



Besides a few living species, this group includes numerous tertiary 

 and mesozoic forms from European horizons, mostly described as 

 Pollicipes. It was evidently a group developed in the mesozoic 

 North Atlantic basin, at that time cut off from the Southern Ocean. 



C. calyculus ( (Aurivillius). Azores, 850-900 meters. 



C. falcata (Aurivillius). Azores, 454 meters. 



C. gemma (Aurivillius). Greenland, 1800 meters. 



C. superba (Pilsbry) . Southeastern United States, 352-440 fathoms. 



C. gnmaldi (Aurivillius). Azores, 845-1,230 meters. 



Genus SMILIUM Gray. 



Smilium Gray, Annals of Philosophy, n. ser., X, 1825, p. 100, for S. peronii, 

 Pilsbry, Bull. 60, U. S. Nat. Mus., p. 13, exclusive of division aa. Proto- 

 scalpellutn Hoek, Siboga-Expeditie, Cirripedia, 1907, p. 58 (for S. poUi- 

 cipedoides, S. aries, S. acutum). 



In this group a median pair of latera lies between the scutum and carina. 

 There are 3 or 4 pairs of latera in all, 13 or 15 plates. Otherwise both 

 sexes are similar to Calantica. In a few species {peronii, uncus) the 

 carina is angular, but in others it has an apical umbo. Most of the 

 known species are Indo-Pacific. Type S. peronii Gray (fig. 1, c, d). 



Dr. Hoek's group Protoscalpellum, of which I take S. pollicipedoides 

 to be the type, differs from Smilium chiefly by having an additional 

 pair of latera in the type species. S. pollicipedoides is interesting from 

 its tendency toward multiplication of basal latera, which Dr. Hoek 

 has discussed with his accustomed insight. 



Smilium and Calantica might without great violence be united as 

 subgenera of a single more comprehensive genus, yet I think the ele- 

 vation of a pair of latera above the basal whorl to the position of 

 "upper latera" is a morphological advance worthy of being signalized 

 by generic distinction. In other characters the two groups are almost 

 identical. The complemental males are alike. 



S. peronii Gray. S. sexcornutum (Pilsbry.) 



;S. uncus (Hoek). S. scorpio (Aurivillius). 



S. pollicipedoides (Hoek). S. acutum (Hoek). 



S. aries (Hoek). S. longirostrum (Gruvel). 



Genus EUSCALPELLUM Hoek. 



EuscalpeUum Hoek, in part, Siboga-Expeditie, Cirripedia, 1907, p. 59, for 

 Scalpellum rostratum, peroni, uncus and stearnsi. 



This genus differs from those preceding chiefly by the more degener- 

 ate males, which are rather sack-like, not distinctly divided into 



