250 Miscellaneous. 



described and illustrated by mj'self in 1874 (' Annals,' vol. xiv. 

 pp. 456 and 4.57, pi. sxi. fig. 27) was the same as that described 

 and illustrated by Mr. R. Hope, F.Z.S., in February last (' Annals,' 

 vol. iii. pi. vi. A-, 5) under the name of "Microciona spinarcus:" 

 nor should I have perceived my error, had not Mr. Hope, in March 

 last, kindly sent me preparations of yet another new species from 

 Hastings, which, from the form of its tricurvate, we both recognized 

 to be totally different from that of 31. spinarcus ; at the same time 

 it seems to me to be absolutely identical with my figure of 1874 

 (I. c), inasmuch as the arms of the latter are depressed almost 

 to straightness, while in the former they are bent much upwards, 

 bow-like (see Mr. Hope's figure, I. c). 



Mr. Hope's second new species of Microciona, viz. that in which 

 the arms of the tricurvate are so much depressed, will be described 

 and illustrated by him hereafter ; meanwhile this statement will be 

 sufficient to correct my own " error," and serve to record the exist- 

 ence of an unnamed and uudescribed British species of Microciona 

 chiefly characterized by the form of tricurvate above mentioned. 



August 5, 1889. 



On the Marine Acarina of the Shores of France. 

 By M. Troubssart. 



Since my previous note on this subject communicated to the 

 Academy on the 5th November, 1888, I have got together fresh 

 materials which enable me to give more complete information with 

 regard to the Acarological fauna of our shores. Besides my personal 

 investigations I have received important contributions from MM. 

 Chevreux and Le Senechal (of Croisic and Caen). Mr. G. S. Brady 

 (of Sunderland) has lent me the types of the species described by 

 him from the English coasts. Lastly, Dr. Lohmann (of Kiel), who 

 has just published an excellent monograph of the Marine Acarina of 

 the Baltic Sea *, has taken the trouble to compare my types with 

 his. 



The only truly marine Acarina are the Halacaridse, which must 

 form a very distinct family, and not a mere subfamily of the Trom- 

 bidiidse. In this latter family the last joint of the palpi is always 

 palpiform, and it is the j^^^nultimate that acquires the form of a 

 terminal claw ; in all the Halacaridse, on the contrary, it is the last 

 joint of the palpi which constitutes the terminal claw, and there is 

 no trace of the palpiform joint. This fundamental difference seems 

 to me to justify the elevation of the Halacaridse to the rank of a 

 family, as proposed by Murray in 1875. 



The Halacaridse live in the sea from the littoral zone down to the 

 depth of 30-50 fathoms. They walk and climb, rather than swim, 

 upon the bottom, the rocks, the Algse, and the fixed or slow-moving 



• ' Zoologische Jahrbucher,' Bd. iv. (1889) p. 269. 



