ZOOLOGY AND BOTANY, MICROSCOPY. ETC. 771 



B. INVERTEBRATA. 



Marine Fauna of the South-west of Ireland-* — The first report 

 of the Committee to investigate the fauna of the hundred fathom line 

 off the south-west coast of Ireland has heen published. Dredgings 

 were made at thirteen stations. Of the Foraminifera sixteen species 

 are new to the British fauna ; Halcampa arenacea and Ghitonactis 

 expansa are new species of Malacozoa ; OpMothrix luetlccni was found 

 to he a characteristic of the deeper water. 



One hundred and thirty-three species of Mollusca Lave as yet 

 been identified. Of the Ostracoda found, Kirthe glacialis has not 

 been previously recorded as recent. 



Ectoparasites of the Gills of Gammarus pulex.|— The first ecto- 

 parasite from the gills of Gammarus pulex, described by Dr. L. Plate, 

 is Dendrocomeies paradoxus. The transparent cuticle has generally, 

 though not always, a double contour. The body substance is not 

 distinguishable into a cuticle and a medullary substance. In addition 

 to the granules which are found in all Acineta3, there are granules 

 which vary greatly in number and size, and are distinguishable from 

 the fat-like grains by the deep stain which they take with safranin. 

 The author calls them " Tinkfcurkorper." They do not blacken with 

 osmium. Their origin and functions are still unknown. ' In addition 

 to these there may be yellowish-brown or green granules. With 

 regard to the number of arms or suckers the author states that in 

 several hundred specimens he never found more than four, and 

 that these always stand in quite definite relation to one another, 

 and to the contractile vacuoles. The arms are not quite stiff, but can 

 be withdrawn into the parenchyma of the body. There is an axial 

 canal in the arms which can always be made out in well-preserved 

 specimens. From the contractile vacuole there is given off a delicate 

 canal which opens on the surface of the body. The nucleus is ovi- 

 form or oval ; there is a distinct nuclear membrane, and the nucleus 

 itself is finely or coarsely granular. After describing the reproduc- 

 tion of the so-called embryos, and the mode of conjugation, the author 

 discusses the relation of D. paradoxus to the other Acinetidfe, and 

 suggests the division of the class into two groups, which he calls 

 Fasciculifera and Eadiformia ; the former contains Ophryodendron 

 and Dendrocometes; the latter Spliserophrija, Podophrya, Acineta, 

 Dendrosoma, and Urnula. Eeproduction is effected solely by the for- 

 mation of internal buds. This is preceded by the elongation and 

 fibrous differentiation of the nucleus, which is followed by the for- 

 mation of a second contractile vacuole. Part of the surface is invagi- 

 nated to form a flask-shaped cavity, which closes later on. This 

 developes four equatorial bands of cilia. The lower surface 

 bulges out in the form of a broad knob, and, after the complete 

 division of the nucleus it separates completely from the parent 

 organism. 



* Proc. R. Irish Acad., iv. (1886) pp. 599-638. 



t Zeitschr. f. Wiss. Zool., xliii. (18S6) pp. 175-241 (2 pis.). 



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