Shulies on marine Oslrarods 181 



Second antenna: — In some forms with sexual dimorphism, in others it is 

 without or almost without it; in most cases it is somewhat more powerfully developed in the 

 males than in the females. — E x o p o d i t e: This branch usually shows a very close agreement 

 in the two sexes. Of about the same length as the protopodite. The proportion between the 

 joints, which always seems to be about the same in males and females, certainly varies a little, 

 but the variations are rather slight. The first joint often attains to about the total length of 

 all the succeeding joints, the second joint is about as long as the total length of the two or three 

 following joints, the third and fourth joints are of about the same length. The first joint has 

 no bristles. The bristle of the second joint is relatively short in comparison with those of the 

 following joints, generally not much longer than the total length of the seven distal joints of 

 this branch, and in some forms even almost completely reduced; in addition this bristle has no 

 natatory secondary hairs, it is either naked or in most cases armed with a varying number of 

 short and more or less powerful, smooth spines and — at least in all the forms of this sub-family 

 described in this work — fitted at the top with a very short and fine hair (sensory htiir?). The 

 bristles of the third to the eighth joints are developed into long natatory bristles, usually fitted 

 with secondary natatory hairs along the greater part of their length. In a few forms some of 

 these bristles are armed with short and more or less powerful spines along a part of their length. 

 In all the forms of this sub-family that are described in this work the distal part of the natatorv 

 bristles was more or less hyaline, somewhat rounded at the point and there fitted with a short 

 and very fine (sensory?) hair. The end joint usually has four bristles, in a small number of 

 forms only three and in exceptional cases, as, for instance, in the genusCrossophorus, a somewhat 

 larger number. Of these four bristles the two ventral ones are long and powerful natatory 

 bristles, not at all or else only rather slightly shorter than the bristles on the third 

 to the eighth joints. The two dorsal ones of them, especially the one situated most 

 dorsally, are, on the other hand, as a rule rather considerably shorter — their length varies, 

 however, pretty considerably in different forms — and generally fitted with a few short secondary 

 hairs; in some forms, however, these bristles too carry numerous long natatory hciirs. In most 

 species smooth basal spines are developed; the end joint is also armed with such a spine. 

 Medially-distally on the third to eighth joints there is usually a series of spine- or hair-like 

 formations, situated more or less closely together, usually rather fine, short, more or less hyaline, 

 most frequently rather difficult to discover; this character seems to vary pretty considerably, 

 so that it is scarcely practical for characterizing the genera and species; nor has it been included 

 in the descriptions given below of forms belonging to this sub-family. Endopodite: This 

 branch sometimes shows strong sexual dimorphism, sometimes, however, it is developed simi- 

 larly in both sexes. In a number of forms it is developed into a jiowerful three-jointed clasping 

 organ in the male; it is usually rather long and distinctly three-jointed, sometimes more or 

 less rudimentary, verruciform and quite unjointed. 



Mandible: — This limb is either without, or in some cases with only very 

 weak, sexual dimorphism. — It is comparatively long and slender. Tlie endopodite 

 is moderately flattened at the sides, its second joint generally considerably narrowed 

 distally. The proportion between the joints, which seems to be about tlie same in 



