FOSSIL CIRFlIPEDES. 947 



two valves *, other than scuta, terga, and carinse, to judge by 

 their structure, none appear to have formed upper ]atera, or at 

 all events to fit between the scuta and terga, as do the upper 

 latera in most forms of ScalpeUum. Moreover, the form of the 

 scuta and terga and the structure of their inner surface shows 

 that the tergal margin of the scutum and the scutal margin of 

 the tergum were in close proximity to each other. In this con- 

 nection Darwin said (1851, p. 44): "I have no doubt that the 

 ridge along the upper occludent margin of the scuta, and 

 that on the occludent margin of the terga, together with 

 their projecting points, are related to each other, owing to 

 the close contact of these valves," It follows, therefore, that if 

 no upper latera were present, the upper whorl of valves in 

 T. tuherculata comprised only five valves, namely, a carina, a pair 

 of terga, and a pair of scuta. The valves of the lower whorl, as 

 mentioned in their description, must have overlapped the bases 

 of the valves of the upper wdiorl, and if we are correct in desig- 

 nating these valves as rostrum, rostral latus, median latus, 

 carinal latus, and sub-carina, the lower whorl would consist of 

 at least eight valves, making thirteen valves for the whole 

 capitulum (see restoration, PI. XCV. fig. 10). 



In the number and arrangement of the valves of the capitulum 

 Titanolepas tuherculata approaches the forms of ScalpeUum 

 grouped by H. A. Pilsbry t under the genus Calantica Gray, and 

 comes nearest to those included by him in the section Scillce- 

 lepas Seguenza, of which the type is S. carinata Phillipi sp., 

 from the Pliocene of Messina, Sicily. The capitula of the species 

 grouped under Calantica closely resemble that of Pollicipes, but 

 diflfer in that there is only a single basal whorl of valves, com- 

 prising three pairs of latera, a rostrum, and a sub-carina. The 

 species included by Pilsbry under the section Scillcelepas are 

 chiefly characterized by the absence of an upper lateral plate in 

 the l^pper whorl, which consequently consists only of five valves, 

 and by the bases of the valves of the upper whoi'l being over- 

 lapped by those of the lower whorl ; the umbo in all the valves 

 is apical. While T. tuherculata agrees with these species in 

 having five valves only in the upper whorl, and in the valves of 

 the lower whorl overlapping those of the upper whorl, it difi'ers 

 from all the species included under the genus Calantica and the 

 section Scillcelepas by the umbo of the scutum being in a sub- 

 central position. 



We have in T. tuherculata^ therefore, a species agreeing in 

 all essential characters with the forms of Calantica {^Scillcelepas), 

 except that it has a more specialized form of scutum. The 



* Two further valves have since been noticed among the Cirripede material from 

 the Chalk detritus of Charing, Kent, in the British Museum (Natural History). 

 These are identical with the valves from Cambridge, which 1 consider to be rostral, 

 and are registered I. 14663, I. 14664. A further rostrum has been found in the 

 Chalk Marl of Burham, Kent. 



t H. A. Pilsbry, "On the Classification of Scapelliform Parnacles," Proc. Acad. 

 Nat. Sci. Philadelphia, 1908, pp. 106-107; "The Barnacles (Cirripedia) contained 

 in the Collections of the U.S. National Museum," Bull. U.S. Nat. Mus. No. 60, 

 1907, pp. 8-9. 



