T. H. Withers — Cirripedes from the Chalk. 29 



Z. Darwini, H. Woodward (1908, p. 493, fig. 1), shows that, as in 

 our specimens, the tergo-lateral and basal margins are nearly straight 

 and almost at right angles to each other, differing much in this respect 

 from the scutal valves of Scalpellum, to which the genus Loricida is 

 most nearly related. Further, in Loricula the occludent margin of 

 the scutum is convex, the umbo is sub-central, and the valves 

 extremely thin and slightly convex, characters also observed in the 

 scuta described above. The inner occludent margin of the scutum is 

 much thickened in Loricula, especially in the region of the umbo, and 

 this is also the case in the valves before us, leaving no doubt that they 

 are rightly ascribed to the genus Loricula. 



Darwin (1851, p. 84) hazarded the opinion that in Loricida the 

 lateral valves of the capitulum must have been present on both sides, 

 and in support of this view Dr. H. Woodward (1908, p. 495) pointed 

 out that in the specimen of L. Darwini figured by him, and in the 

 example of L. pulchella, var. minor, figured by Fritsch & Kafka 

 (1887, p. 2, pi. i, fig. 2), the inner margin of the under scutum could 

 "be seen projecting from beneath the occludent margin of the upper 

 scutum. Decisive proof of the paired nature of the lateral capitular 

 valves in this genus had, however, already been given by Whiteaves, 

 for in the holotype of his L. canadensis (1889, p. 190, pi. xxvi, figs. 4, 

 4a) the upper lateral series of capitulum plates have been either 

 partially or completely broken away, showing underneath the inner 

 surfaces of the scutum, tergum, carinal latus, and the upper or middle 

 latus. The under row of sub-rostral (or sub-scutal) plates of the 

 peduncle can also be seen projecting from beneath the upper row in 

 the figured example of L. Darwini. 



So far, then, there is conclusive proof that the three lateral plates of 

 the capitulum, as well as the row of sub-scutal plates of the peduncle, 

 w r ere present on both sides of Loricula ; but whether the three central 

 rows of peduncular plates are also present on the under side is still 

 doubtful. In fact, after removing the chalk from beneath one of the 

 three specimens of L. Darwini studied by him, Dr. H. Woodward 

 found that the three principal (central) rows of the elongate scales of 

 the peduncle were absent. He then suggested that they were not 

 developed upon the under side of the peduncle, but that the animal 

 was fixed to the Ammonite shell, to which Loricula has always been 

 found attached, along the margins formed by the under row of the 

 carinal and sub-rostral (or sub-scutal) valves. Bearing on this 

 question is a fact which does not appear to have been attended to. 

 Among the specimens of Z. pulchella figured by Fritsch & Kafka 

 (1887) and those of Z. Darwini studied by H. Woodward (1908), 

 some show the right side uppermost, with the scutum on the left hand, 

 and others the left side uppermost, with the scutum on the right hand. 

 Although it appears probable from this that the whole of the peduncular 

 valves were developed on both sides of Loricida, it is by no means 

 conclusive proof, since it may be quite accidental as to which side of 

 the animal was developed uppermost, in the same way that certain 

 lobsters have the ' crushing chela ' developed on the right side and 

 others on the left. 



Z. expansa differs from all other species of Loricula, including 



