576 SUMMARY OF CURRENT RESEARCHES RELATING TO 



batch. They are carried by the mother in the usual way in crabs, and, 

 so far as is known, are hatched not as zoa?as, but in a much more 

 advanced stage, and the young stay in the mother's brood-pouch until 

 they have attained the adult form and a considerable size. The author 

 discusses the differentiation of species and varieties and the geographical 

 distribution. 



Structure of Fresh-water Ostracods.* — Alfred Bergold has investi- 

 gated the internal structure of various species of Gypris, and describes 

 the alimentary canal, the lip-glands, the excretory organs (associated 

 with the first antenna?, the second antenna?, and the maxilla?), the 

 maxillipede gland, and the female genital apparatus. 



The mesenteric epithelium shows a typical " stiftchensaum." The 

 cells are both secretory and absorptive. The three segmental organs (of 

 first and second antenna? and maxilla?) are excretory ; the labial glands 

 and maxillipede glands are secretory. In the female genital apparatus 

 there are three distinct parts : — the vagina with a copulatory vesicle, 

 a spiral canal with a receptaculum seminis, and a copulatory or cement 



gland. 



Lemseodiscus.f — Max Kollmann points out that in various internal 

 features, notably in the structure of the testis, Lernseodiscus approaches 

 Saccidina and diverges from PeJtogaster. The study of the whole struc- 

 ture confirms this view. It seems impossible to derive Lernseodiscus 

 from PeJtogaster, as Smith has proposed. The approximation of Lernseo- 

 discus to Saccidina and Heterosaccus does not present any difficulty. 

 Indeed, Lernseodiscus may be compared to a Heterosaccus whose mesen- 

 teron has been greatly developed to right and left. 



Decapod Natantia of Coasts of Ireland.} — Stanley Kemp reports 

 on 47 species of Decapoda Natantia collected by ss. ' Helga.' Ten species 

 are practically restricted to the littoral and laminarian zones, such as 

 Hippolyte variant, Leander squilla, and Grangon vulgaris : these and 

 some others are also found in brackish water ; several species, such as 

 Pandalus montagui and PandaUna brevirostris may be reckoned as 

 seasonal visitors to the laminarian zone ; the great majority live on or 

 very close to the bottom. The following species have, however, been 

 taken under circumstances which afford the clearest proof that they are 

 free-swimming — Amalopenseus elegans, Sergestes robustus, S. arcticus, 

 Pasiphae sivado, Parapasiphae sulcatifrons, Acantliephgra purpurea, 

 A. debilis, Hymenodora glacialis, Garidion gordoni. Of these, Pasiphae 

 sivado and Garidion gordoni occur constantly on the bottom, but are 

 nevertheless sometimes found in midwater, usually in soundings of no 

 considerable magnitude. The seven remaining forms are, as a general 

 rule, bathypelagic, but Sergestes robustus and Acanihephyra purpurea, 

 having been found in the stomachs of fish which are known to frequent 

 the ocean floor, must be regarded as members of the benthos as well as 

 of the nekton. 



A few species are definitely associated with other animals : Typton 



* Zool. Jahrb., xxx. (1910) pp. 1-42 (3 pis. and 3 figs.). 



t Ann. Sci. Nat. (Zool.) x. (1909) pp. 255-73 (1 pi. and 6 figs.). 



X Scient. Invest. Fisheries, Ireland, 1908, i. (1910) pp. 1-190 (23 pis.). 



