348 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



and on a level with the adjacent surface of the carapax except poste- 

 riorly, where a small oval area of the extremity of the lobe is exposed 

 by a depression in the carapax. This oval area is thin, semitranslucent, 

 and not calcareous, and has every appearance of being a true corneal 

 area, although I am unable to detect any evidence of facets. The cara- 

 pax along the margins of the sinus is in close contact with the ophthal- 

 mic lobe but is not really connected with it. From the lower portion of 

 each ophthalmic lobe there is an elongated, cylindrical and somewhat 

 conical, but obtuse and pointed, protuberance, of which the base rests 

 in a transverse groove in the base of the antenna, whiJe the terminal 

 portion extends well across the open, ventral side of the orbital sinus. 

 Upon the obtuse extremity of this protuberance there is a nearly circu- 

 lar area similar to the cornea-like area at the posterior extremity of the 

 dorsal part of the lobe. 



Unfortunately the specimen is not in sufficiently good condition to 

 enable me to determine positively in regard to the structure of these 

 cornea-like areas, but that they are connected with the optic nerves 

 and are sensitive to light there is, I think, no chance for reasonable 

 doubt. While it seems probable that all four of these areas are really 

 faceted like the eyes of ordinary Podophthalmia, it is possible that they 

 may be large, simple, or nearly simple eyes, like the eyes of some Am- 

 phipoda and Cumacea. The division of the ophthalmic lobe each side 

 into two or more "eyes" has not, I think, before been noticed among 

 the Decapoda, and is certainly an interesting fad in morphology, but it 

 is apparently not a character of much systematic or phylogenetic value. 

 Among the Schizopoda, the lamellar expansion of the ophthalmic lobes 

 in Amblyops, and their broad expansion and partial union in Pseudom- 

 ma, are quite as remarkable and apparently somewhat similar modifica- 

 tions ; and Ampelisca and Biblys, among the Amphipoda, are cases in 

 which there are two simple eyes each side, while in the closely allied 

 Kafploops the number apparently varies in the different species. 



The peduncles of the antennulne (figures 1, 2) are very stout, being 

 stouter even than the peduncles of the antennae. The basal portion of 

 the proximal segment is longer than the two distal segments, is armed 

 on the distal portion of the outer margin with two spiniform teeth, and 

 the inner side is broadly expanded and prolonged into an acute scale- 

 like appendage upturned and densely ciliated along the inner margin, 

 and extending considerably beyond the distal segment and nearly as far 

 as the tip of the antennal scale (&, figure 2). The second and third 

 segments are subcylindrical, and, as seen from above, are each about as 

 broad as long, the second being somewhat larger than the third. The 

 inner or major iiagellum is about as long as the carapax. The minor 

 flagellum is about as long as the peduncle of the antenna, about half as 

 thick as the base of the major flagellum, of nearly uniform thickness 

 for two-thirds its length, then tapers rapidly to a very slender tip, and 

 is thickly ciliated along the inner margin distally. 



