9 Crust. 
CltUSTACEA. 
developed. He states that the most Brachyara and all Anomura of which 
the development is known, leave the egg in the stage of Zoea^ but only 
a few Macrara (for instance, Crangon) do so ; Gecarcinua among the 
Brachyura, and A stacus among the Macrura^ are hatched in a later stage, 
that of Megalopa\ P emeus and Euphausia in an earlier one, that of 
NaupUus ; Palinurus in a quite special stage, that of Phyllosoma. Rep. 
Br. Assoc. Dublin, 1878, pp. 193-209, pis. v.-vii. j part of the figures 
copied from Muller and Metschnikoff. 
F. Muller repeats his reasons for considering the NaupUus, which he 
caught as free-swirnming animals, to be the larva of Peneus ; Z. wiss. 
Zool. XXX. p. 163, translated Ann. N. H. (5) i. p. 481. C. S. Bate 
states that this is a mere supposition, not founded as yet on direct 
observation, and as no other Macrurous Decapod is known to be hatched 
in the NaupUus form, he suggests that the larva observed by Muller may 
be that of some Schizopod, or even of a Suctorian Cirriped ; Ann. N. H. 
(5) ii. pp. 79-85. A. Giard replies to this that the development and 
the males of SaccuUna and Peltogaster are known (cf. Zool. Rec. xi. 
p. 220), and that Muller’s NaupUus cannot be related to any of them ; 
tom. cit. pp. 233 & 234. 
Reichenbach’s paper on the embryology of the common Crayfish 
[Zool. Rec. xiv. Crust, p. 3] is abstracted in Q. J. Micr. Sci. xviii. 
pp. 85-94, pi. vi. 
A. Giard states that the larva of a species of Entoniscus living on 
Grapsus varius has a distinct median eye besides vestiges of the lateral 
eyes, which he regards as an indication of the NaupUus stage hitherto not 
known in the Isopods. Assoc. Fr. vii. Paris, 1878, p. 747, also C. R. 
Ixxxvii. pp. 299-301, and Bull. Sci. Nord. (2) i. pp. 237-240, translated 
Ann. N. H. (5) ii. p. 347. 
P. Mayer (MT. zool. Stat. Neapel, i. 2, pp. 165-179, pi. v.) fully con- 
firms Bullar’s discovery that in the Cyrnothoidoe each individual is in its 
early stage male, and afterwards female [Zool. Rec. xiv. Crust, p. 5]. 
The genital organs make their first appearance as one piece on each side, 
consisting of four lobes ; three of these become the testes, and very soon 
(in Cymothoa at a size of 8-14 mm.) are filled with spermatozoids, all 
stages of development of which can clearly be seen. At this time the 
two vasa deferentia and the two penes at the seventh thoracic segment 
are open, and the young Cymothoa is still swimming,' its abdominal feet 
being provided with natatory bristles. Afterwards, when the animal is 
fixed on fish, the fourth lobe developes itself into an ovary, the vasa 
deferentia are closed, and after one or more moults, the external male 
organs are lost ; meanwhile, the oviduct and the female orifice at the 
fifth thoracic segment are formed. Self- fecundation is not effected (true 
hermaphroditism), as the spermatozoids pass out at the side of the not 
yet fully developed ovary without entering it, but each individual, when 
young and free, fecundates an elder one, and is later, when fixed, fecun- 
dated by a younger one (protandry). This is corroborated by the fact 
that in young individuals the stiliform appendage in the abdominal feet 
is present, which is seen in other Isopods, and seems auxiliary to copu- 
lation ; and that a younger and an elder individual are often found near 
