296 CARL BOVALLIUS, AMPHIFODA HYPKKIIUEA. I. 2. HYPEKIlDJi;. 



EtUheinisto tint.urctha. 



» — — Ultimate pair of pleopoda having the peduncle more than four times tlie length of 

 the telsoD, and the rami half as long as the peduncle, with the margins scarcely serrated; pen- 

 ultimate pair reaching a little beyond the extremity of the peduncle of the ultimate; ante- 

 penultimate reaching a little further than the extremity of the penultimate. Telson lanceolate.» 



In the same publication Si'ENCE Bate briefly described a supposed new species 

 Themisto Guerinii, saying that the uniarticulate flagellum of the second pair of antennse 

 »is one of the chief distinctions" from Th. antarctica. After giving some further dis- 

 tinctions, which easily are explained from the difference in age of the two specimens, 

 he says: 



»The rest of the animal corresponds with the description given of T. antarctica. In fact, 

 the species so much resemble each other, that, had not their respective size and locality been 

 very distinct, they probably would have been passed över as varieties of the same.» 



I have examined specimens in the collection of the »Miasée d'Histoire naturelle» in 

 Paris labelled: ^iThemisto — Latitude de la Platå — L'Astrolabe. (63)», without doubt the 

 very type specimens of the British author; they were in a både state, but proved clearly to 

 be females and young males of Euthemisto antarctica, after niy diagnosis above; and 

 of this reason I have put Th. Guerinii as a synonym for Euthemisto antarctica, Dana. 



In 1879 Geo. M. Thomson described Themisto antarctica from the sea off New 

 Zealand, and nothing in his description goes against his view that the animal in question 

 is identical with Dana's species. His description closely agrees with that given by 

 Spence Bate. 



In 1888 Stebbing identified one of the species represented in the »Challenger» 

 collection ^vith that descrilied by Thomson, and gave to it the new name Euthemisto Tliom- 

 soni. In my opinion Stebbing was not right in this identification, and overlooked that 

 his E. Gaudichaudii was the same species as the Themisto antarctica, described by Thomson, 

 and thus, according to my opinion, the true Euthemisto antarctica. Dana. Stebbing's 

 E. Thoinsoni, on the other hand is considered here to be identical Avith the true Euthe- 

 misto Gaudichaudii, Guérin. The chief characteristic which induced Stebbing to deny 

 the identity of Thomson's species Avith Dana's was the statement of the former author 

 that the body is dorsally carinated in the adult animals, which characteristic Dana does 

 not mention, but in all the older specimens of all the species which I have examined, 

 namely Euthemisto libellula, E. antarctica, E. Gaudichaudii, and E. compressa, the body 

 is dorsally carinated. The development of this carina is however very varying from one 

 individ ual to another within each species, and is usually less distinct in an ovigerous 

 female than in a mala of the same size. This feature has thus in my opinion no value 

 at all for specific distinction. A comparison of the diagnoseis, given in this treatise for 

 Euthemisto antarctica and E. Gaudichaudii, with the descriptions and drawings given 

 by Stebbing for E. Gaudichaudii and E. TJiomsoni will support, I hope, my views as 

 to the synonymy adopted here. 



As the drawings given by Stebbing 1. c. pl. 172 of an elder, but not fully adult, 

 male, and pl. 173 of a younger one, are very good, 1 find it unnecessary to publish my 



