26 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
INVERTEBRATA. 
Freshwater Fauna of the Azores.* — Mr. J. Richard gives an account 
of the freshwater fauna of the Azores, as observed on the visits of the 
yacht £ Princess Alice.’ A short account is here given of the Ostra- 
coda, Copepoda, and Cladocera. Attention is called at the same time to 
the presence in the islands of Plumatella repens , and the discovery in 
them, for the first time, of the genus Mermis. It appears to be certain, 
notwithstanding some doubts, that the remarkable rotifer Pedalion 
mirum does exist in the Azores. The author recommends the study of 
the island of Flores, the peculiarities of which show that it merits a 
thorough zoological exploration. 
Adelotacta Zoologiea.f — Sig. F. S. Monticelli describes under this 
title ( = of doubtful classification) two remarkable forms, Pemmatodiscus 
socialis g. et sp. n. and Treptoplax reptans Montic, The former is a very 
simple organism, corresponding to the gastrula type, with two layers 
of epithelium separated by a coelomic cavity. The outer layer is a high 
ciliated epithelium with characteristic rhabditoid structures : the inner 
layer is lower and non-ciliated. A distinct ciliated mouth puts the 
gastrular cavity in communication with the outer world. There are no 
traces of organs or sexual elements, but the organism multiplies by 
division, which is, of course, an argument against its being a larva. It 
was found in cysts in the jelly of Rhizosloma pulmo. The author com- 
pares it to Korotneff’s Gastrodes parasiticus. 
The second form, which the author described in 1893, is also very 
simple, and has three strata — an external dorsal of flattened non-ciliated 
cells ; an external ventral of elongated, clavate, flagellate cells ; a me- 
dian of large, irregularly polygonal elements in three rows. Adhering 
to the lower surface of the dorsal stratum are numerous refractive cor- 
puscles or globules enclosed in modified cells. The animals were found 
adhering to the sides of the aquaria at the Naples Station. They change 
their form incessantly, like Amoebae, and multiply by division. Monti- 
celli compares it in detail with other forms, especially Trichoplax ad- 
hserens. He concludes that Trichoplax , Treptoplax, and Pemmatodiscus 
must at present remain Adelotacta. 
Mollusca. 
Indian Deep-Sea Molluscs.:} — Mr. E. A. Smith describes twelve new 
species of deep-sea molluscs, collected by the survey steamer ‘ Investi- 
gator.’ Some of these are extremely interesting on account of their re- 
markable form and surface ornamentation ; others are peculiar on account 
of their close similarity to species which occur in the North Atlantic ; 
in one instance the author can find indeed no distinguishing features 
between the Atlantic and Indian Ocean specimens. 
Mode of Life of Lima hians.§— Dr. J. D. F. Gilchrist has an inter- 
esting article on this mollusc, great quantities of which are to be obtained 
by dredging off Millport. The two organs of most importance are the 
* Bull. Soc. Zoo!. France, xxi. (1896) pp. 171-8. 
f MT. Zool. Stat. Neapel, xii. (1896) pp. 432-62 (2 pis.), 
i Ann. Mag. Nat. Hist., xviii. (1896) pp. 367-75. 
§ Trans. Nat. Hist. See. Glasgow, iv. (1896) pp. 218-25. 
