366 EEV. T. E. E. STEBBING ON NEW SPECIES OF AMPHIPODOUS 



which I have been able to discover in the collection should include ten distinct species, 

 of which no less than seven are new. One may without rashness forecast that, if 

 species continue to multiply at this rapid rate, before long it will be thought necessary 

 to relegate such forms as acanthodes, stenopus, and undpes to so many separate genera. 



Family RHABDOSOMID^. 



In his admirable work on the Oxycephalids, published in 1890, Dr. Bovallius 

 separated from the Oxycephalidse a new family which he named Xiphocephalidae, 

 distinguished by having the eyes planted between an outdrawn nock-like portion of 

 the head and a long needle-shaped rostrum, by having the telson articulated to the 

 preceding segment, by having tlie fifth pair of penieopods reduced to a single bladder- 

 like joint, and by the absence of marsupial plates from the ovigerous female. 

 Dr. Bovallius recognized that the 'Challenger' species Bhahdosoma brevicaudatum, 

 as described, formed an exception, by having its telson coalesced with the preceding 

 segment, and that his own genus Tulbergella, with the fifth peraeopods four-jointed, 

 was in that respect intermediate between the other Oxycephalidae, whicli have those 

 limbs fully jointed, and the Xiphocephalidse, in which he supposed them to be limited 

 to a single joint. After the publication of his book he came to England and inspected 

 the type specimen of Bhahdosoma Irevicaudafum at the British ^Museum. He persuaded 

 himself that the telson was in fact articulated ; but from a re-examination of the 

 specimen I am myself convinced that the original description was correct, and that anv 

 appearance to the contrary is due to the transparency of the animal, making it some- 

 what difficult to perceive that the ventral suture is not dorsal. There is now to be 

 described another short-tailed Bbabdosoma, in which likewise the telson is coalesced 

 with the preceding segment. No stress, therefore, can properly be laid on the 

 articulation of the telson as a family characteristic. In yet another new species of 

 Bliahdosoma the fifth peraeopods prove to be three-jointed, thus making a close 

 approach to what is found in the acknowledged Oxycephalid genus Tulbergella. Even 

 the neck-like constriction and the needle-shaped rostrum of the Rhabdosomid head are 

 met with, though in far less exaggerated form, among the Oxycephalidae, so that it 

 seems inconsistent on the part of Dr. Bovallius to rely on these as points of distinction 

 between the two families, while, on the other hand, he introduces into the Oxycepha- 

 lidse the very different-looking and blunt-snouted Simorhyncotus. The effect of the 

 latter innovation is at least very awkward for the received nomenclature, since the 

 family name, which signifies that the beak is sharp, is made to cover a genus the name 

 of which signifies that the beak is blunt. There still remains for the Xiphocephalidae 

 the substantial distinction that the female is unprovided with marsupial lamellae, and 

 carries her eggs in the singular manner which Dr. Bovallius has described. The reason 

 for changing the name Xiphocephalidae into Rhabdosomidse will be apparent from the 



