A REVIEW OF THE MYSIDACEA 15 



but, unless this represents a third character in which my specimens 

 differ from those described by Hansen and Fage, I think that Fage's 

 specimens too must have had the apex of the telson damaged. 



The question now arises as to the interpretation to be placed on these 

 differences. A glance at Willemoes-Suhm's drawings published in the 

 Challenger Report will show that the Challenger specimen agreed with 

 the specimens from stations 4919 and 4960 in the characters of the 

 rostral plate and antennal scale. In the description published by Sars 

 from Willemoes-Suhm's notes the rostral plate is described as follows : 

 "Anteriorly, it [the carapace] projects as a short, but very broad, 

 frontal plate, abruptly truncate at the extremity, the anterior margin 

 being slightly emarginate and finely serrate, the lateral corners some- 

 what extended." This is precisely the condition in the two specimens 

 from stations 4919 and 4960. The lateral view of the Challenger speci- 

 men shows three teeth on the outer margin of the antennal scale in 

 addition to the terminal tooth, the dorsal view six. 



The specimens from stations 4919 and 4960 clearly represent the true 

 C. alatum, and if the specimen from station 4334 and those described by 

 Hansen and Fage are to be regarded as a different species, it is to these 

 specimens that a new name must be given. 



However, another explanation may be given for the facts. The 

 C/iallenger specimen was obviously a female, for the incubatory 

 lamellae are shown in the figure. Both Hansen's and Fage's speci- 

 mens were males, and I think the differences between them and the 

 Challenger specimen can be explained as secondary sexual characters. 

 It is in this light that I regard them. Unfortunately, I cannot con- 

 firm this conclusion from the present material, since in none of the 

 specimens is there any trace of incubatory lamellae and the mate- 

 rial is not sufficiently well preserved to show the position of the geni- 

 tal openings. In fact, I cannot with certainty give the sex of the 

 specimens. The examination of better preserved material must be 

 awaited to settle the entire question but the evidence available is 

 sufficiently good to warrant the suggestion that all the material be- 

 longs to one species with well-marked secondary sexual characters. 

 The geographic distribution of the species, as available from pub- 

 lished literature, does not indicate that two separate species are in- 

 volved. 



Genus LOPHOGASTER M. Sars 



Lophogaster M. Saks, 1857, p. 160. 

 Ctenomysis Norman, 1862, p. 151. 



I have found myself in the same difficulty as Ortmann (1906) in 

 determining the species of Lophogaster in this collection, at least 

 those specimens that appear to be very closely allied to the type 

 species, L. typicus, and yet cannot be referred to it with any confi- 



