308 MR. E. J. MIERS ON THE PEN^ID^E. [Mar. 5, 



wider interval than the preceding. Cephalothorax and postabdornen tonier.tose. 

 Terminal segment not carinate, with minute lateral spines. 



17. P. affinis, Edw. 

 Indo-Pacific region. 



Rostrum and cephalothorax as in P. affinis. Postabdornen naked. Termi- 

 nal segment with the deep longitudinal median sulcus defined by lateral carina, 

 and with lateral spimdes. 



18. P. consfrictus, Stimpson. 



East Coast United States. 



Rostrum somewhat sinuated, 9-dentate above, with the teeth equidistant. 

 Terminal segment without lateral spines. 



*19. P. tenuis, Dana. 

 North Patagonia. 



Rostrum styliform toward apex, nearly straight, 6-dentate above near its 

 base ; the last tooth separated by a wider interval. Terminal segment without 

 lateral marginal spines. 



*20. P. avirostris, Dana. 



Singapore. 



B. Rostrum very short, not reaching beyond the eyes. 

 * Rostrum slender. 



Eye-peduncles long. Rostrum not half as long as the eyes, 7-dentate above. 



*21. P. podophthalmus, Stimpson. 

 Hong Kong. 

 Eye-peduncles of moderate length. Rostrum a little shorter than the eyes, 



5-dentate above. 



*22. P. gracilis, Dana. 



Sooloo Sea. 



Eye-peduncles thick. Rostrum scarcely reaching beyond them, 8-9-dentate 

 above. (5th ? legs greatly elongated, with the dactylus nearly half as long as 

 the cephalothorax.) 



*23. P. stenodaetylus, Stimpson. 



Hong Kong. 



** Rostrum laminiform, high, and laterally compressed. 

 Rostrum 9-10-dentate above. Flagella of the antennules half as long as 

 the peduncle. 



*24. P. lamellatus, De Haan. 



Japan. 



Rostrum 6-dentate above. Flagella of the antennules about as long as the 



peduncle. 



* 25. P. brevicomis, M.-Edw. 



Indian Seas. 



Aristeus edwardsiantjs. (Plate XVII. fig. 3.) 

 Penceus edwardsianus, Johnson, P. Z. S. 1867, p. 897. 

 The typical example of this very fine species is in the collection 

 of the British Museum ; and I have little hesitation in referring it 

 to the genus Aristeus of Duvernoy (Ann. Sci. Nat., ser. 2, Zool. xv. 

 p. 101, 1841). The character principally relied upon by Duvernoy 

 for the distinction of the genus was derived from the ramose structure 

 of the branchiae, which he conceived were formed upon a different 

 type from that found in other genera of the Caridea ; but I am able, 

 from an examination of the branchiae of A. edwardsianus, to con- 

 firm Dana's observation that they do not differ essentially in struc- 



