1900.] FEOM TILE FALKLAND ISLANDS. 543 



7. Apical lobes on basal joint of first antenna. — This feature is 

 found wanting by Sars in the species he calls splendens and gracilis, 

 as also in his own species similis and mucroaata. Of his antarctica 

 he says : " Antennular peduncle slender, without any dorsal lobe, 

 but with the outer corner of the basal joint produced into a sharp 

 spine." Ortmanu's species schotti agrees in this respect with 

 antarctica, except that the sharp spine instead of being small is 

 very elongate. As already mentioned, it is not at all certain that 

 the true splendent and gracilis of Dana are without the lobe, 

 or that the true pellucida of Dana has it. The value of this 

 character is further somewhat impaired by its variability, since in 

 his description of bidentata Sars says : "In must of the specimens 

 this lobe is divided into two acuminate lappets (fig. 3) ; but in some 

 specimens, though differing in no other respect from the typical 

 form, these lappets are much more numerous, forming a dense 

 fringe along the free edge of the leaflet (tig. 4)." Dr. Ortmann 

 says of gibboides, " basal joint of the inner antennae above with an 

 oval, obliquely forward and outward pointed lobe;" and of pseudo- 

 gibba, "basal joint of the inner antenna? above with a triangular 

 lobe, whose point is directed forward and outward." But the tri- 

 angular lobe is not figured, and the oval one is, in the figure, itself 

 apu-ally pointed and verging on the triangular. 



There are also lobes occurring on the second and third joints of 

 the first antennae which are available, though they have not yet been 

 found important for specific discrimination. 



8. The basal scale of the second antennae, and the attendant basal 

 spine. — The extent to which the scale reaches beyond the peduncle 

 would be a useful character, but information on this point is rather 

 deficient. Apparently bidentata is distinguished from all other 

 species by the fact that its basal spine extends far beyond half the 

 length of the scale. 



9. Mandibular palp. — Unfortunately for several species the 

 features of this palp are known imperfectly or not at all. Judging 

 froui Dana's figure of it in Euphausia superba, that species agrees 

 in this particular with antarctica of Sars, in which the palp in 

 question is very slender, its terminal joint being nearly as long as 

 the median. This is not the case in pellucida Dana, miiileri 

 Claus, bidentata Sars, splendens of Sars, or gracilis of Sars, the last 

 having " the terminal joint very small and oval in form." 



10. Second maxilla. — The shape, size, and armature of the 

 apical joint seem to offer tangible characters for specific distinction, 

 but such as can only be discovered by dissection. 



11. Proportionate length of the joints in the three pairs of maxilli- 

 peds arid the three developed pairs of perceopods. — The value that 

 might attach to this character is strikingly illustrated by a com- 

 parison of the figures drawn by Sars of the last of these appeudages 

 in bidentata and antarctica. In the former species the third joint 

 is shorter than the fourth, in the latter it is much longer than all 

 the four succeeding joints combined. Unfortunately, beyond this 

 one comparison, there is scarcely any definite and trustworthy 



36* 



