Miscellaneous. 25 1 



marine animals of which they are commensals. Their food appears 

 to be very varied, according to age and locality. It is the colour of 

 the food which fills their stomach and marks its outlines, which, 

 when seen by trauslucence, gives the coloration remarked in several 

 species, for the integuments are transparent and of a nearly colourless 

 testaceous-yellow tint. If my observations are correct, Halacarus 

 spinifer, Lohm., the largest and commonest species of our coasts, is 

 exclusively carnivorous in its youth ; the larvte and nymphs are of 

 a coral-red colour, identical with that of the ova of Copepods which 

 abound in the region inhabited by them ; the adult, on tlio con- 

 trary, is of a darker or lighter brown, and we find in its stomach 

 numerous tests of Diatoms, indicating at least a partially vegetable 

 regime. Like many other Acarina, therefore, these animals are 

 parasites in their youth, and become simple commensals when adult. 

 The Halacaridce live well in brackish water, and even resist fresh 

 water for a long time. They can be kept alive for two or three days 

 in an aquarium of the latter kind, while Copepoda die there rapidly. 

 In the canal from Caen to the sea, the water of Avhich has scarcel)- 

 more than 2 gr, of salt in the litre, M. Le 8enechal has found Hala- 

 carus spiuifer upon the Hydroids which have become acclimatized 

 there. 



But it is in the Laminarian zone, or, more correctlj', in the Coral- 

 line zone, and especially upon Oorallina officinalis, that these animals 

 abound, as is shown by the numerous dredgings which M. E. Chev- 

 reux has been good enough to make specially at my request upon 

 the coast of the Croisic. The Halacaridse occur in great numbers 

 attached by their hooked feet to the delicate fronds of the Corallines. 

 In M. Chevreux's flasks these animals are mingled with hundreds 

 of small Crustaceans (Copepods, Amphipods, and Ostracods), with 

 Pycnogonidte and specimens of Amphiura sqwimmata, collected at 

 the same time. These results agree with those obtained by Dr. 

 Lohmann in the Baltic ; of the fifteen species collected by him two 

 occur in the zone of red seaweeds (Corallines) at .depths of 5-10 

 fathoms. 



The number of species from the French coasts which I shall make 

 known in a memoir now in course of preparation is comparatively 

 considerable. My collection contains seventeen species, while the 

 English naturalists have only recorded ten, and Dr. Lohmann fifteen. 

 The individuals from the Ocean are superior in size to those of the 

 Baltic, although several species are identical, such as Rhomhognathus 

 (Aletes, Lohm.) notops, H. Seahami, Halacarus spinifer ( = H. cterio- 

 pus of my previous note), if. Miirrai/i ( = H. inermis), H. Fabricii, 

 H. rhodostigma, and Leptognathus falcatus, which inhabit our At- 

 lantic shores. 



Two generic types (Leptopsalis and Copidognathns) characterized 

 in my former note occur in the Ocean and are wanting in the Baltic. 

 A new species of the former genus [Leptopsalis Cltevreuxv) will 

 enable this type to be better characterized. It occurs at the Croisic. 

 This applies also to Pachygnathus scidpAus, Brady, a species which is 

 very interesting as having been dredged at a depth of 35 fathoms. 



