468 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
the internal surface of the ovary, and, except in the Hysidae, along its 
whole length ; in Macrura and Paguridfe the vulva is the only ecto- 
dermic portion of the int rnal reproductive organs ; in Dromiidm and 
Brachyura the ectoderm is invaginated to form a vagina and a seminal 
reservoir ; the receptaculum seminis is a diverticulum of the vagina ; 
the aggregating material in the receptaculum resembles fluid chitin. 
In Macrura, the cement-glands are situated just under the epidermis 
on the internal surface of the epimera and on the ventral surface of the 
lateral laminae of the telson ; the Thalassinidae and Stenopus are excep- 
tional in having the glands restricted to the pleopods ; in Paguridse 
the glands occur in 12-16 groups on the ventral and lateral surfaces of 
the pleon, near the pleopods and in the anterior labriform expansion ; 
in Homola and in all Brachyura the receptaculum acts as a cement- 
gland. 
In Brachyura and in Anomura the eggs are fixed to the hairs of 
the internal branch of the pleopods, in Palinuridae and Astacidae to the 
hairs on the stalk of this branch, in Caridae to the hairs on the abdo- 
minal surface and on the basal joints of the first four pleopods, in 
Lucifer near the last pair of thoracic appendages. In Penaeidae the 
eggs are not fixed, perhaps because no incubatory chamber can be 
formed. It is likely that the cement-glands are modified glands of the 
appendages (“ Beindriisen ,r ). The ova have at first a single membrane 
or chorion which becomes chitinous, but they subsequently acquire a 
second envelope formed from the cement-glands. 
Copulation is always preceded by a moult, first of the male then of 
the female. When a receptaculum is developed, the ova are fertilized 
as they pass the opening of the seminal reservoir ; when there is no 
receptaculum, they are fertilized as they are liberated. The cementing 
substance may serve as a medium through which the spermatozoa reach 
the ova, into which they pass in all likelihood through the pores of the 
chorion. 
Compound Eye of Macrura.* — M. H. Yialanes is of opinion that 
Patten’s views on the morphology and physiology of the eye have not 
the general character which he claims for them ; each of the segments 
of the cone, far from being continuous with the rhabdoms, terminates 
in a filament which becomes attached to the basal membrane. In other 
words, the cone is to be regarded as merely an organ of refraction. 
The nerve-fibres do not terminate in the protoplasm of the retinal 
cells, but are directly connected with the rhabdoms. Each of the seven 
rhabdomeres is connected with a special nervous tube, and it is, there- 
fore, very probable that each ommatidium may be the point of departure 
of at least seven distinct luminous sensations. 
Development of American Lobster.| — Dr. F. H. Herrick gives a 
somewhat detailed account of the development of the American lobster. 
The animal appears to spawn at a definite period of the year, and 
copulation to precede oviposition by a considerable period. 
There is great irregularity in the segmentation ; the period of 
incubation is about three hundred days. Some remarkable variations 
* Compte8 Rendus, cxii. (1891) pp. 1017-9. 
t Zool. Anzeig.. xiv. (1891) pp. 133-7, 115-9. 
