G'tCi On an Example o/Scalpellum fossiila. 



the length of L. grayce. L. sarlei, J. M. Clarke, from 

 the Niagara Shales (Silurian) of Rochester, New York, 

 has thirteen plates to a complete sliell, hut this measures as 

 much as 2-3 mm. L. arayce would seem to he more nearly 

 related to L. squamatulus (Barrande), from the Ordovician 

 of Bohemia, and L. suecicus, Moberg, from the Upper Ordo- 

 vician of Sweden— two species that appear to be very close 

 indeed to each other. No shell approaching completeness 

 is known of the two latter species, although a number of 

 plates of L. suecicus have been found in association, but the 

 plates would appear to be in many instances longer in pro- 

 portion to their breadth than is the case in L. yraya, and the 

 growth-ridges number from 8-9 to a millimetre, but with 

 no intervening and almost equally prominent ridges as in 

 L. graya. 



LXXVIII. — An exceptionally complete Example of the 



Cirripede Scalpellum fossula, Darwin. By Thomas II. 



AVlTHEKS, F.G.S. 



[Plate X. fig. 0.] 



(Published by permission of the Trustees of the British Museum.) 

 Some years ago (1911, Geol. Mag. dec. v. vol. viii. p. 21), 

 when describing certain Cirripedes in the collection of 

 Dr. H. P. Blackmore, F.G.S. , I mentioned that he had a 

 beautiful example of the species Scalpellum [Arcoscalpellum) 

 fossula, well worthy of description. Owing to its fragile 

 nature, however, it was dangerous to risk sending this 

 important fossil through the post, but .«iiice Dr. Blackmore 

 has recently very generously presented it to the Geological 

 Department of the British Museum (Registered In. 21559), 

 it is now possible to proceed with its description and illus- 

 tration. 



While detached valves of this species are fairly common 

 in the Upper Senonian, it is quite exceptional to find the 

 valves in their natural association. Darwin (1851, Pal. 

 Soc. Monogr. Foss. Lepadidie, p. 24) described two speci- 

 mens from the Chalk {Belemnitella mucronata-zone) of 

 Norwich, each with four valves in position, one specimen 

 consisting of the carina, scutum, tergum, and upper latus, 

 and the other of a carina, scutum, tergum, and carinal latus. 

 Dr. Blackmore's example from the Chalk {Actinocamax 

 quadratus-AOi\e) of East Harnham, near Salisbury, Wilts, 

 consisting as it docs of fourteen valves in the capitulum, 

 together with some of the plates of the peduncle, is by far 



