290 Transactions. 



new var. be immature forms of the general type, and the non-development 

 of the umbonal teeth be thus accounted for ? It seems certainly not pos- 

 sible. The umbonal teeth are uniformly absent in fully developed forms 

 down to the smallest. And in L. anatifera general type the tooth is 

 uniformlv present from the smallest to the best-developed specimens. This 

 ensures that the new variety is not an immature form of L. anatifera 

 general type nor of L. australis. 



This new variety of L. anatifera next affects the present classification 

 and distinction of L. anatifera and L. killii. The latter is known by — ■ 

 (1) no umbonal teeth on either scutum ; (2) 3 filaments on each side of 

 the body. 



In other respects, including the mouth parts, it is closely similar to the 

 general type of L. anatifera. The maxillae and mandibles in all the varieties 

 of L. anatifera and in L. hillii are practically indistinguishable. I have put 

 my new variety under L. anatifera, rather than under L. hillii, because the 

 former is a most widely distributed species, and because an external um- 

 bonal tooth seems more likely to vary than a filament. The calling of 

 this new variety a new species would have certainly nothing to justify it. 

 What is left is to regard the following specific characters now as certainly 

 distinctive :— 



L. anatifera : 2 filaments ; umbonal teeth absent or on right scutum 



only. 



L. hillii : 3 filaments ; umbonal teeth absent. 



L. australis: 2 filaments: umbonal teeth on each scutum in adult; 

 and the following small, fairly reliable characters : wide carinal fork, 

 brittle valves showing curved occludent margin, and 3 spines on maxilla. 



Any one can then distinguish the known specimens of these without 

 the confusion and difficulty at present attending their classification. 



When preserved in spirit, certainly all three species are very similar in 

 size and general appearance. 



The other members of the genus will give little difficult v. 



As for other characters often given, I know of no others certainly dis- 

 tinctive. I have specimens from each of the three species which show that 

 (a) radiating lines on the valves, (b) proximity of carina to the other valves, 

 (c) apex of carina being rounded or acuminate, {d) the distance the carina 

 extends up between the terga, and (e) the curvature of the occludent margin, 

 cannot be used as accurate guides in distinction. The great variability 

 of all these characters in specimens I have examined belonging to L. 

 anatifera alone makes them of little use in distinguishing L. hillii and 

 L. australis. 



It will be seen, then, that such statements as the following now require 

 modification :— 



(1.) "The smoothness of the valves, together with the presence of a 

 tooth on the right-hand scutum, and its entire absence on the left-hand 

 side, is an unfailing diagnostic mark " of L. anatifera. (Darwin, " Mono- 

 graph Cirripedia : Lepadidae," p. 77.) 



(2.) L. anatifera " Carene separee des autres j>l<iq<ies par un espece mem- 

 braneux tres etroit on nul." (Gruvel, " Cirrhipedes,'' p. 108, 1905.) 



(3.) L. anatifera : " It resembles L. hillii, but may be distinguished by 

 the faintly striated valves, the presence of an umbonal tooth in the right 

 scutum, none in the left, and the proximity of the base of the carina to the 

 scutum." (Pilsbrv, " Barnacles of United States National Museum, 1907.) 



