34 Memoirs of the Indian Museum. [Vol. Ill, 



excellent drawings of the different stages owing to the abundance and excellent state 

 of preservation of the material at my disposal. These drawings will supply that 

 which is chiefly lacking in previous accounts, since the illustrations of the metamor- 

 phosis in Darwin's work do not exhibit more than the external outlines of the larvae, 

 and in Hoek's report in the '' Challenger " series the only larvae figured are those 

 of Lepas australis, Darwin, Scalpellum regium and trianguläre, Hoek (8, pi. ii, figs. 

 I — 4). This author's report on the " Siboga " expedition contains an illustration of 

 the pupa of 5. stearnsi, Pilsbry (g, pi. vi, fig. 10). 



On the other hand, the development of the different organs — cement glands, 

 ovaries and testes — from the cyprid to the adult has not been thoroughly traced as 

 yet, and although Hoek (8) describes correctly the cement glands and the ovaries in 

 both the cyprid and the adult, he does so with some doubt as to the correctness of 

 his identification. I have been able to obtain a complete series of examples from the 

 cyprid to the fully grown adult. 



2. The anatomy of the parasitic males has also been somewhat fully dealt with. 

 Darwin (5) described Scalpellu n vulgare, ornatum, rostratum, peronii, villosum, and 

 Ibla cumingii and quadrivalvis , with plates of Ibla cumingii, of Scalpellum vulgare, 

 peronii, villosum and rostratum. Hoek (8) classifies the males in three groups accord- 

 ing to their condition of degeneracy and refers to twenty-four species of Scalpellum. 

 He describes minutely the male of Scalpellum regium (Wy. Th.), which in many 

 respects is identical with that of 5. gruvelii. The males of the three species described 

 in the present paper would be referred, in the case of 5. squamuliferum, to Hoek's 

 class I, as showing a distinct capitulum and peduncle; in the case of 5. gruvelii, to 

 class III 3 without division to capitulum and peduncle and without rudimentary 

 valves. 5. bengalense should be placed in class II. 



In the report on the " Siboga " expedition (9) Hoek describes the external charac- 

 ters of the males of /ô/a sibogae, H., with figures, oi Scalpellum pollicipedoides, H,, 

 acutum, H., rostratum, D., uncus, H., stearnsi, Pilsbry, chitinositm, H., inflatum, H., 

 javanicum, H., polymorphum, H., distinctum, H., pellicatum, H., crinitum, Yi., gracile, 

 H., hexagonum, H., fissum, H. 



Gruvel in the Arch, de Biol. (6) gives a full account of both the external and 

 internal anatomy of the male of Scalpellum vulgare, and in the reports on the 

 ''Travailleur" and ''Talisman" collections (7) he deals with those oi Scalpellum 

 peronii. Gray, villosum, Leach, longirostrum, Gruvel, gigas, H., hoeki, Gru., striatum, 

 Gru., lutium, Gru., and velutinum, H. 



3. The cirripedia have a special interest for students of biological theory, in 

 that they offer examples of the evolution of dioecism from hermaphroditism. The 

 facts of the case, as is well known, were first brought to light by Darwin (5), who 

 showed that within the group there occurred (i) true hermaphrodites — e.g., Lepas ; (2) 

 andro-dioecious forms — such as Scalpellum peronii ; and (3) dioecious forms — Scal- 

 pellum ornatum and Ibla cumingii. 



Hoek (8, p. 18) elaborated this idea. By cutting serial sections of Scalpellum 

 regium he confirmed Darwin's view as to the purely female nature of the large form 



