i6o 



looked at from above, in the former the outer margin of the branchiostegal spine runs parallel 

 with that of its fellow, the spine being directed straight forward and distinctly shorter 

 than the 2°'^ joint of the antennal peduncle; in Hetcroc. laevigatiis, on the contrary, the much 

 larger spine projects by half its length beyond the s"'' joint of the antennal peduncle, 

 reaching as far forward as the eyes, and its outer margin is distinctly curved inward. 



As regards the abdomen, both species fully agree with one another. 



The antennular peduncle reaches just beyond the middle of the antennal scale, the 2°'' 

 article is a little longer than the 3''^, and the stylocerite, the outer margin of which is concave, 

 extends almost to the far end of the peduncle; the flagelia are probably of equal length, 

 65 mm. long, nearly as long as carapace and rostrum combined. 



Antennal scale (Fig. 37) about half as long as the rostrum, distinctly narrowing anteriorly 

 and about 3'/o-times as long as broad, presenting its greatest width at the posterior fourth ; in 

 Heteroc. gibbosus the antennal scale appears a little broader in proportion to its length 

 and the outer margin appears a little more convex. Antennal flagellum 240 mm. long, 

 twice as long as the body. 



The external maxillipeds, the terminal joint of which is almost I'/o-times as long as the 

 penultimate, project as far forward as the antennal scale; exopodite rudimentary, iY.2mm. long. 



Legs of the i^' pair a little shorter than the external maxillipeds. 



The shorter stouter leg of the 2"'' pair is placed on the right side; carpus 7-jointed, 

 the I*' and the last joint of the same length and slightly shorter than the 5 other short and 

 equal joints combined; chela little shorter, but broader than the carpus, fingers hardly 

 shorter than the palm. 



While this leg extends only by the fingers beyond the antennal peduncle, its slender 

 fellow reaches to the tip of the antennal scale. 



This species also differs from Heteroc. gibbosus Bate by the much shorter dactyli of 

 the 3 posterior legs, which, as regards their other relative proportions, agree with this species. 

 In a male of Heteroc. gibbostis from Stat. 256, that has about the same size as the male of 

 Heteroc. laevigatus^ the propodus and the dactylus of the 3'^' leg are respectively 14,5 mm. 

 and 5,2 mm. lung, in the male of Heteroc. laevigatus^ however, these numbers are 12,75 mm. 

 and 2,4 mm., the dactyli (Fig. 37^) measuring in this species only about one-sixth, in 

 Heteroc. gibbostis about o n e - 1 h i r d of the propodi ; in Heteroc. gibbosus the dactylus is 

 slender, nearly g-times as long as wide at base, and armed along the proximal half of its 

 lower margin with 6 S2:)inules, that increase in length from the 1^', near the propodus, to the 6"''; 

 in Heteroc. laevigattis it has a stouter shape (Fig. 37*5), being only about 5-times as long 

 as broad at its base, and there are only 5 spinules on the lower margin, that reach to beyond 

 the middle, besides the spinule at the base of the claw, and these spinules are comparatively 

 also slightly larger than in Heieroc._ gibbosus. It is remarkable, indeed, that this character, by 

 which the two species may so easily be distinguished, has hitherto been overlooked. 



Heteroc. laevis A. M.-Edw. is a different form, distinguished, besides by the characters 

 mentioned at p. 1 64, by the rostrum proper being armed dorsally with 4 small teeth and by 

 the branchiostegal spine being small and reaching less far forward than the orbital spine. 



