Zoology. 541 
The marine shells of Fernando Noronha, ana indeed most of 
the marine fauna and flora, are by H. N. Ridley stated to show 
affinities to those of the East Indies. The species Trochus have 
a southern distribution. 
CrustaceaA.—Another part of Dr. De Man’s Crustacea of the 
Mergui Archipelago has appeared, embracing pages 177 to 240, 
and plates 13 to 15. It includes the conclusion of the Grapside, 
the Leucosoids and the major part of the so-called Anomura. The 
series is especially valuable from the fact that the author has had 
access to the types of the French carcinologists. So far the species 
enumerated number 135. 
M. Chevreux and Guerne call attention to the amphipod, 
Cyrtophewm chelonophilum, a commensal. of Thalassochelys caretta, 
seventy-seven specimens of which have been collected in the scien- 
tific voyages of the Prince of Monaco. This species differs from 
those previously known by the shortness of the antenne, and is. 
probably a native of both hemispheres. 
After Rathke, in 1837, noticed the curious fact that the Palæ- 
mons infested by Bopyrus belonged exclusively to the female sex, 
all succeeding authors have confirmed his observations. Neverthe- 
less, guided by previous discoveries concerning the effects of para- 
sitie castration among certain decapodous crustaceans infested by 
the Rhizocephala, M. Giard last year gave forth the hypothesis. 
that the facts noticed by Rathke were true in appearance only, and 
that though all the Palzemons fount with Bopyrus seem to be of 
he female sex, this was really the result of the atrophy of the male 
organ produced by the parasites. M. Giard has recently been able 
vee this supposition, both on European and other species of 
æmon. ; 
„MYRIAroDs.—C. H. Bollman publishes in a small pamphlet 
Without indication of place of publication, a preliminary list of the 
Myriapods of Arkansas. Forty species are catalogued, of which 
nine are regarded as new. + 
FisuEs.—Mr. George Brook (Proc. Royal Phys. Socy. of Edin- 
burgh, x.) monographs the British species of the genus Zeugopterus, 
enumerating three species, Z. punctatus, unimaculatus, and papillo- 
sus, the last being a new species found in the Clyde. 
Mr. Geo. Brook (Proc. Roy. Soc. Edinburgh, 1887) states that in 
the trout the segmental duct arises from the ectoderm. Its first 
appearance is in an embryo of twenty-seven days, when it forms a. 
well-marked thickening in the middle trunk region. The lumen of 
the duct arises as an irregular cavity, and later the whole tube sepa- 
cites from the ectoderm and sinks into the intermediate cell mass, 
Far observations that he has made on the chick seem to indicate- 
^at a similar origin of the duct occurs in birds. 
According to the observations upon the food of fresh-water- 
