On some Cretaceous and Tertiary Cirrlpedts. 1G7 



sinuate, its posterior angles diluted ; mesonotum (including 

 the crucitorm elevation) almost as long as head and pro- 

 notuin t'igether ; abdomen longer than space between apex 

 of liead and base of cruciform elevation ; tympana completely 

 exposed, coverings entirely absent ; face more or less centrally 

 sulcate; rostrum reacliing the intermediate coxie ; opercula 

 small, transverse ; abdomui beneath with the lateral margins 

 broadly recurved; tegmina and wings semiopaque; tegmina 

 with the basal cell about twice as long as broad; apical areas 

 short in length, eight in number, a curved rudin)entary vein, 

 curved inwardly, crossing tegmen from base of first ulnar 

 area to base ot lower apical area; ])osterior tiijiaj with a few 

 fine spines. 



Type, T. cuj)ieosi>ai\^a, Uhler [Tiblcen). 



XXV. — Some Cretaceous and Tertiary Cirripedes referred to 

 Pollicipes. By Thomas H. Withers, F.G.S. 



[Plates VII. .t VriL] 



The Cirripedes discussed in this paper include certain sessile 

 forms belonging to the family Brachylepadidie and a number 

 of pedunculate forms of the family Pollicipedidce. For the 

 sake of convenience, they are dealt with in the following 

 order: — (1) the species herein referred to the genus Brachy- 

 lepas ; (2) a group of species now included in a new genus 

 Fycnolepas ; and (3) certain species that can now be proved 

 to belong to the more primitive forms of Scalpellum [sensu 

 lato) included in the subgenus Scillcelepas of the genus 

 Calantica. All these have been hitherto referred to Pollicipes. 

 Darwin, in his Monograph on the fossil pedunculate 

 Cirripedes, distinguished the whole of the described species 

 as either Pollicipes or Scalpellum. and determined certain 

 characters by which one could distinguish the separate valves 

 of the species belonging to tliose two genera. Except for 

 the more advanced forms of Scalpellum (sensu lato), these 

 distinctions can no longer be followed, and as our knowledge 

 of the fossil pedunculate forms increases, it becomes more 

 evident that the reference of many of these to the genus 

 Pollicipes cau not J)e maintained : indeed, it will probably be 

 found eventually that very few really belong to that genus. 



