Crustacea.] SUBANTARCTIC ISLANDS OF NEW ZEALAND. 623 



The synonyms given above require some justification, seeing that Bovallia and 

 Eusiroides are placed by Stebbing in different families. I find that my specimens 

 agree well with Stebbing's description of E. crassi ; they also agree closely with his 

 description of E. monoculoides (Haswell), except that the posterior border of the 

 third segment of the pleon is not serrate, or shows only one or two minute indications 

 of serration. The absence of this serration appears to be the only distinction between 

 these two species, and probably examination of a fuller series of specimens would 

 show that it does not always hold. Under the name " E. caesaris, Steb., var.," 

 Mr. Walker has described from Ceylon a form that has only three teeth on the hind 

 margin of the third pleon segment, and thus appears to be intermediate between 

 E. crassi and E. monoculoides, to the latter of which Mr. Stebbing has now united 

 E. caesaris. The supposition that E. monoculoides and E. crassi are forms of the 

 one species appears to be borne out by the geographical distribution, for the single 

 type specimen of E. crassi was taken in the South Atlantic, off Monte Video, at a 

 depth of 600 fathoms, while E. monoculoides is already known to be widely distributed 

 in the South Pacific and Southern Indian Oceans, in Australia, and at Heard Island ; 

 and one would naturally expect specimens from Auckland Islands to belong to this 

 species rather than to one found only in the South Atlantic, if this were really a 

 distinct species. 



From the above considerations I had come to the conclusion that it was inex- 

 pedient to continue to look upon E. crassi as a species distinct from E. monoculoides, 

 from which Mr. Stebbmg has himself said that it differs little ; and I felt the more 

 justified in combining the two because my specimens, although without distinct 

 dorsal teeth, have the first and second segments of the pleon slightly produced and 

 a little compressed dorsally, and in one specimen the seventh segment of the peraeon 

 shows the same thing to a slight degree, in these respects agreeing with E. mono- 

 culoides rather than with E. crassi. It appears evident that in this species, as in 

 others to which attention has been directed by Walker and other writers, the pre- 

 sence or absence of dorsal teeth on various segments of the body is subject to con- 

 siderable variation. 



After arriving at this conclusion my attention was accidentally drawn again 

 to the figures of Bovallia gigantea given by Chevreux, and to the great resemblance 

 which they bore to my specimens ; accordingly I compared them carefully with 

 Chevreux's description and figures, and found that they agreed with these quite as 

 well as they had done with Stebbing's description of E. crassi. In Chevreux's 

 specimens the last segment of the peraeon and the first and second of the pleon are 

 produced dorsally into teeth, though evidently to a greater degree than shown in 

 my specimens. This difference in degree, however, would naturally be associated 

 with the greater size of the specimens, as his figure was taken from a female measuring 

 32 mm, in length, while my largest specimen, also a female, measures only about 

 26 mm. Pfeffer's specimens were even larger, being 45 mm. in length. In my speci- 

 mens the setae and calceoli are arranged on the antennae in the same general way 

 as described by Chevreux for Bovallia gigantea, though they are hardly so numerous ; 

 but this, again, is naturally to be expected in smaller specimens. I find a very small 

 one-jointed accessory appendage on the upper antenna, just as described by Stebbing 

 in Eusiroides, though in mine it is of still smaller size than in his specimens ; in 

 Chevreux's specimens it appears to be absent altogether, as might naturally be ex- 



