299 



wide in the middle, is a little wider than that of the female of A. peuuata, in which these 

 numbers are 12,5 mm. and 10 mm. The i st or median carina and the 2 nd or dorsal carinae 

 differ not from those of A. pennata, the median carina is composed of 10 teeth or tubercles, 

 the left dorsal of 8, the right of 9; all are rather prominent and sharp, though decreasing in 

 size and prominence from before backward. The huge, wing-like and sharp spine at the anterior 

 extremity of the lateral carina reaches to the level of the middle of the 3 rd antennular article; 

 this spine is but slightly turned outward, much less than in A. pennata, so that the 

 distance, 10,75 mir "i between the apices is even a little smaller than the greatest width of the 

 carapace in the middle. Orbital spine nearly as long as the rostrum. Behind the terminal spine 

 ancl the deep cervical groove the lateral carina is armed with two teeth, of which .the anterior 

 is sharp and reaches almost to the level of the orbital margin, while the posterior is much 

 smaller and subacute. The posterior moiety of the lateral crest resembles that of ./. pennata 

 (Bate) var. affinis Alcock (Illustrations Zoology "Investigator", Plate LI, fig. 3), it ends ante- 

 riorly in a sharp tooth behind which to the posterior margin occur 5 smaller ones; the i st or 

 anterior is also sharp, but the following are obtuse. In the typical pennata one observes usually 

 but one trifling tooth behind the sharp spine at the anterior extremity. The supra-marginal 

 carina, which in A. pennata is smooth, appears in A. Siöogae distin ctly serrate by 13 

 or 14 processes, that are all obtuse excepting the anterior which is acute; the processes are 

 smail, little prominent. Branchiostegal spine acute, reaching as far forward as the huge anterior 

 spine of the lateral carina. The antepenultimate thoracic sternum (Fig. 72^) is armed in the 

 middle with a strong, laterally much compressed tooth, the sharp tip of which is 

 curved forward. A similar, but much smaller and hardly compressed tooth occurs 

 mi the penultimate sternum, but the posterior sternum is smooth, without any tracé of carination, 

 though the anterior boundary appears slightly thickened, just in the middle. 



The abdomen is sculptured exactly after the same pattern as that of A. peiniata, but 

 the sculpturing is much more prominent. Like in A. peiniata, on either side of the median 

 crest of the 2 nd somite (Fig. 72 c/), that ends anteriorly in a curved tooth, occur two tubercles, 

 which are separated by a deep vertical furrow. The two submedian carinae of the ^ h somite 

 are entire and terminate posteriorly in a small sharp tooth, whereas they are armed in 

 A. pennata with a small acute tooth just behind the middle. The tergum of the 6 th somite is a 

 little broader in proportion to its length and the two submedian carinae are therefore a little 

 more remote from one another; each is trispinose, the posterior spine being a little longer than 

 the two anterior. The abdominal pleura resemble those of A. pennata, but the lower apex is 

 less sharp, on the i st and 2 nd subacute, on the following rather blunt. 



Eyepeduncles a little smaller than those of A. pennata. Antennulae and antennae like 

 in this species. 



The external maxillipeds project by their terminal joint beyond the tip of the antennal 

 peduncle and have a less slender form than those of A. pennata. The peraeopods of the i st 

 pair that bear a short setose exopodite, differ from those of A. pennata by their stouter 

 shape (Fig. 721? and Fig. "joe); in the ovigerous female of A. pennata the chela without the 

 dactylus is 7,5 mm. long and 1,9111111. broad in the middle, in the type of A. Sibogae, however, 



