1908]  Decapod Crustaceans. 27 
long had its corresponding branches 8 mm. (42 artieulations) and 
9 mm. long. 
Thus while the outer branch of vulgaris is only slightly 
shorter than the inner and reaches beyond the blade-shaped appen- 
dage (scaphocerite) of the 2nd Antennae, in Allmanni the outer 
braneh is only about half as long as the inner one and does not 
reach beyond the scaphocerite on the 2nd Antennae. These 
characteristic differences were found in every instance in å con- 
siderable number of females of both species. In vulgaris the number 
of artieulations on the outer branch was always more than in 
Allmanni. 
In the case of males of both species the branches of the lst 
pair of antennae differ only slightly in length, and reach beyonå 
the scaphocerite of the 2nd antennae. Females as well as males 
of both species have the outer branch broader than the inner: but 
the males have a slightly broader outer branch than females have. 
Eyes (tig. 1) of Allmanni are manifestly larger than those 
of vulgaris. "The facetted portion is broader than the ophthalmopod. 
whereas in vulgaris it is of about the same breadth: the ophthal- 
mopod moreover is slightly shorter than the same member in 
vulgaris. 
It will be seen from the drawing (tig. 1, A & 1, B) that the 
scaphocerite on the 2nd antennae of vulgaris is rather more produced 
in its anterior portion than it is in Allmanni. This was usually the 
case; though in a number of specimens the scaphocerite was in 
this respect approximately the same for both species. 
Rostrum ot vulgaris å shade more acute than that of Allmanmni. 
Oral parts corresponded very closely in the two species. 
The lamellar outer branch (exopodite) on the 2nd maxilla seems 
in vulgaris to be a little shorter and proportionally broader than 
that of Allmanmi. The epipodite of Ist maxilliped in Allmanni was 
found to vary in size: its frontal extremity was sometimes shorter some- 
times longer than the pedunele of the exopodite within. The length 
of the epipodite of 1st maxilliped is practically the same as for 
vulgaris. | 
C. Allmanni has on the whole å more elongate body than 
vulgaris, as will appear from the habitus-figures of two nearly 
