24 PROCEEDINGS OF THE NATIONAL MUSEUM. \ol. xxxi. 



together 9 males and 1 female; the third from Key West {Fish Hawk 

 stations Nos. 7282, 7283, 7286). 



The northern specimens, from the Carolinas, compare with the 

 European (and South African) form in the following particulars: 



(1) The rostrum is longer, generally about as long as the peduncle 

 of the antennula, but in two specimens (males) it is shorter than this 

 peduncle, although longer than in the typical form; and in 2 females 

 from Station No. 2602 it is slightly longer than this peduncle but dis- 

 tinctly shorter than the antennal scale. 



(2) The antennal scale has on the outer margin a greater number of 

 teeth; the normal number seems to be 6 or 7; five specimens have 6 

 teeth on both sides; two specimens have 6 on one side, and 7 on the 

 other; one female has 7 teeth on both sides. Besides, there is one 

 specimen with 6 teeth on one side, and three with 7 teeth on one side, 

 while the other side could not be determined owing to its damaged 

 condition. Finally, one female has 6 teeth on the right, and 5 on the 

 left side. Thus 5 to 7 are the numbers found, 5 once, 6 fourteen 

 times, 7 seven times. 



(3) In the number of lateral teeth of the telson, these specimens agree 

 well with the European form, the usual number being 3 on each side. 

 There are, however, a few exceptions. Four specimens have 3 teeth 

 on one side, but only 2 on the other; one specimen has 3 teeth on one 

 side and 4 on the other (female, Station No. 2602), and one (male, 

 Station No. 2601), has 1 spine only on each side, placed at a differ- 

 ent level, the right one being more proximal than the left one. 



Those from the Mexican Gulf have the following characters: 



(1) The rostrum is in one case only shorter than the peduncle of the 

 antennula; in seven specimens it is longer than this peduncle, but 

 shorter than the antennal scale; and in one case (Station No. 2399) it is 

 about as long as the antennal scale (in the remaining individual it is 

 damaged). Thus the average slightly exceeds that of the northern set. 



(2) The antennal scale has in seven cases 6 teeth on both sides; in 

 one case there are 6 on one, 7 on the other side; and in two cases there 

 are 7 teeth on both sides. This agrees well with the condition found 

 in the northern set. 



(3) The telson has uniformly 3 teeth on both sides, with one excep- 

 tion, where there are 2 on the right and 3 on the left. This seems to 

 be the normal condition in Atlantic specimens. 



The specimens from Key West (6 males, 2 females), collected by 

 the U. S. Bureau of Fisheries vessel Fish Hawk, agree very well with 

 the Gulf form. The rostrum is as long as the peduncle of the anten- 

 nula, except in two cases, in which it is slightly longer. The antennal 

 scale has generally 6 teeth, but in two specimens there are 7 on the 

 right side. The telson has 3 teeth on each side, but in two specimens 

 there are 2 teeth on one side and 3 on the other. 



