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Show 540 REV. T. R. R. STEBBING ON CRUSTACEANS [May 22, did, though it was on his part done in a somewhat tentative manner. On the whole, the identification of the 'Challenger' specimens with Dana's E. splendens seems to rest on a rather insecure foundation. A third form is described by Sars as without doubt the Euphausia gracilis of Dana, a decision for which there is strong support in the figure given by Dana of his single, somewhat damaged, specimen. Still, even here there is room for remark. Sars says: " Antennular peduncle without any dorsal lappet, basal joint shorter than the other two taken together;" but Dana says: " First joint of inner antennae sparingly produced and acute at apex," and figures it as decidedly longer than the two other taken together. Sars says that the inner plate of the uropods is much longer than the outer. Dana, in a detail-figure, represents the outer fully as long as, if not slightly longer than, the inner. Dana says: " Feet very slender, last three joints subequal, and together but little shorter than preceding joint." As already intimated, Dana carelessly speaks of these proportions as though they applied to all the feet indiscriminately, instead of varying in each pair. There is, however, reason to believe that he bases his statements on the last (developed) pair. In his lateral view of the animal the three terminal joints of the last leg appear in fact subequal, but together much longer than the preceding joint. As there is no detail-figure of the limb, there is no need to insist on the inconsistency between the figure and the description. But in the lateral view given by Sars the last three joints of the undescribed last leg are very unequal. Also the detail-figure of the gill of the last (rudimentary) leg, which is given by both authors, may possibly represent the same structure, but twins would never be confused if they were as little alike as these two drawings. Of the large and splendid Euphausia superba Dana, Sars, like Dana, had but a single specimen. The agreement between the figures and between the two accounts where they touch one another, though not absolute, is sufficient to make it probable that both authors are treating of the same species. Next after the four forms originally included in the genus comes Euphausia mulleri Claus, 1863, from Messina. In regard to this it is curious and perplexing that, while Sars deems it unquestionably identical with what he considers to be Euphausia pellucida Dana, Claus himself declares that it stands nearest to, without being the same as Dana's, Euphausia splendens. In one notable particular it agrees better with pellucida, both of Sars and Dana, than with the splendens of either of these authors-namely, judging by the detail-figure, it has the inner branch of the uropods reaching decidedly beyond the outer. Claus, however, in the text makes no mention of this character. On the other hand, he distinguishes his own species from splendens as being longer (16-18 mm.), as having a longer rostral projection, and the sixth pleon-segment relatively much shorter. The two latter distinctions are not borne out by his figure as compared with Dana's. From E. pellucida of Sars one might say that E. mulleri is distinguished by a shorter |