THE AMPHIPODA. 37 



variations in size are perplexing, M. Bonnier recording an ovigerous female 10 mm. in 

 length from a depth of 950 metres in the Bay of Biscay, while Sars speaks of North 

 Atlantic specimens 17 mm. long, and others wholly agreeing with these except in being 

 taken at much less depths and in scarcely exceeding a length of 5 mm. Dr. G. H. 

 Fowler mentions specimens from Valentia, Galley Head, and the Firth of Forth, the 

 curious fact about which is " that they are all very small, ranging from 2 to 5 mm. ; 

 whereas in the Faeroe Channel they are mostly about 7-10 mm. in length." Bovallius 

 gives the length as 5-8 mm. 



Boeck makes a dorsal carina characteristic of the genus, and Bovallius describes the 

 body in this species as feebly cariuated, less distinctly in the female than in the male. 

 This account would not be inconsistent with a disappearance of the carina from very 

 small or young specimens. Vosseler says of the young specimens which he had 

 examined that none had any indication of a dorsal carina, nor could I detect any such 

 indication in specimens of the present collection. Only one of these approached the 

 length of 4 mm. 



Very small specimens, apparently belonging to this genus and perhaps to this species, 

 have the first and second peraeopods even more like those of Hyperia luzoni than shown 

 in Vosseler's plate 8. fig. 1, representing the first perseopod of a young female 

 " Farathemisto ohlivia ? " Since, however, there are other very small species of 

 Farathemisto, it may be doubted whether the younger forms, measuring from 1 to 

 2 or 3 mm. in length, can be with any certainty discriminated. A careful studv 

 of adults and young taken together may in future supply marks of distinction 

 for the young of the several species, but the little isolated specimens of the present 

 collection do not furnish materials for such a study. Yet a specimen only 3"5 mm. long, 

 with articulation in the flagella of the antennae becoming visible and thus indicating an 

 approach to maturity of the male sex, closely agrees with the figures of F. ohlivia given 

 by Bovallius and Sars, in regard to the telson and uropods agreeing with Sars rather 

 than Bovallius. In the third pera>opods the fifth joint is rather longer than in the fourth 

 pair, and there rather longer than in the fifth. Bovallius speaks of all these limbs as 

 equal in length ; but Sars qu.alifies them as subequal. 



The specimen just referred to was taken at Station 21, at the surface. A specimen of 

 the same size, with antennae doubtful, was obtained at Station 21 m, between 500 and 

 400 fathoms. A smaller male occurred at Station 21 ti, between 150 and 100 fathoms. 

 A specimen occurred at Station 21 o, between 200 and 100 fathoms. Others, for the 

 most part smaller than those mentioned, were taken in various hauls between the 

 surface and depths ranging to 100 fathoms. The largest specimen in the collection, 

 measuring 375 mm., was taken at Station 22 e, at the surface. 



EuTHEMiSTO, Bovallius, 1887. 

 1889. Euthemisto, Bovallius, K. Svensk. Vct.-Akad. Handlingar, Bd. xxii. No. 7, p. 275. 



Gu^rin's Themisto, 1825, being preoccupied, was changed to Euthemisto by Bovallius 



in 1887. 



