8 THE VOYAGE OF H.M.S. CHALLENGER. 



Smith ' (1880) observed Tetraclita porosa and Lepas anatifera in a collection of 

 Crustaceans from Vancouver and Queen Charlotte Islands. 



Ryder 8 (1870) observed a specimen of Platylepas decorata, Darwin, upon 



Lepidosteus. 



These arc all the new facts which I have been able to bring together relating to the 

 number and geographical distribution of the living Cirripedia, and published since the 

 appearance of Darwin's Monographs. In this department — as I have already said — the 

 increase of our knowledge has not been considerable. The same may be said with 

 respect to the fossil species. The results arrived at by Darwin are well known, and 

 may be briefly summed up as follows : — 



The genus Pollicipes embraces the oldest known Cirripeds, — Pollicipes ooliticus from 

 the Lower Oolite, Pollicipes concinnus from the Middle Oolite, &c. In the Upper Chalk 

 and the so-called Maestricht Formation the number of species known is the greatest. 



The genus Scalpellum is the second ; it makes its appearance in the Lower Greensand, 

 and is represented by about the same number of species as Pollicipes in the Upper Chalk. 



The genus Loricula comes next ; the species described by Darwin is from the Lower 

 Chalk. It is the only genus of fossil Cirripedia of which no recent representatives are 

 known. 



The genus Verruca is the first of the sessile 3 Cirripedia which makes its appearance. 

 The oldest known species, Verruca prisca, is found fossil in Chalk, and in the Maestricht 

 Formation. All the other sessile Cirripedia are represented in the Tertiary stages only. 



The genus Balanus is represented by a single species in the Eocene ; the number of 

 species increases towards the younger Tertiary deposits, but Darwin believes that if all 

 the species of Balani hitherto found in the several Tertiary formations, from the Eocene 

 to the Glacial deposits, throughout Europe, were collected together, they would not 

 amount to twenty species. The number of recent species described by Darwin amounts 

 to forty -five. 



The genera Acasta and Pyrgoma are each represented by a single species in the 

 Coralbne Crag. Of both genera Darwin has mentioned nine living species. 



The genus Coronula appears for the first time in the Red Crag. At present the 

 genus numbers three species. 



In 1857 a very interesting paper of Bosquet 4 was published on the fossil Cirripeds 

 of the so-called Maestricht Formation. This paper contains the description of one new 



1 Smith, S. J., Notes on Crustacea collected by Dawson at Vancouver and the Queen Charlotte Islands, Rep. 

 Progr. Geol. Suri'H, Canada, 1878-79. 



2 Ryder, John A., American Naturalist, July 1879. 



3 Darwin considers the VerrucidcB as a distinct family— according to him, therefore, Balanus is the oldest known 

 genua of sessile Cirripedia. 



4 Bosquet, J., Notice sur quelques Cirripedes recemment decouverts dans le terrain Cretace du Duche de Limbourg, 

 Natuurk. Verhamdel. v. d. IIoll. Maats. v. JVetensch. Tweede Verzamel., xiii., 1857. 



