»o. 1480. SCHIZOPOn CRUSTACEANS— ORTMANN. 25 



The largest West Atlantic specimen is a male from Station No. 2401, 

 measuring 2i> mm. The few females at hand are all small and measure 

 between 16 and 18 mm. 



A series of fifteen specimens, 9 males and 6 females, from six stations 

 off Honshu Island, Japan, was examined. None of them were found 

 to be smaller than 21 mm.; the females were between 21 and 27 mm., 

 and two of them (24 and 27 mm.) were gravid; the males being between 

 22 and 32 mm. Thev have the following characters: 



(1) The rostrum is comparative^ long, even longer than in the 

 West Atlantic form, which in turn exceeds the average found in the 

 Hawaiian. There is not a single individual in which it is shorter 

 than the peduncle of the antennula. In three (2 males and 1 female) 

 it is about as long as this peduncle, while in all others it is distinctly 

 longer. Generally it is shorter than the scale of the antenna, but in a 

 few cases it is of equal length. 



(2) The antennal scale has generally onl} T 3 teeth on the outer mar- 

 gin; in one individual (male, 31 mm.) there are 2 on the right and 3 

 on the left side, and in another one (male, 27 mm.) the reverse is the 

 case. Thus these specimens represent the opposite extreme of that 

 seen in the West Atlantic form. The Hawaiian form is intermediate 

 with 3 to 5 teeth. 



(3) The telson generally has 2 spines on the lateral margins on 

 each side. Four specimens, however, constitute an exception, having 

 1 spine on the right side and 2 on the left. 



The above records show that these characters can not be regarded as 

 of specific value. Taking the European and South African form as 

 the type, the West Atlantic specimens agree with them in the spines 

 of the telson, while all the Pacific specimens possess the tendency to 

 reduce their number. The rostrum is shortest in the typical form, 

 but in all others shows a tendency to become longer; the Hawaiian 

 form comes close to the typical in this respect, while both the West 

 Atlantic and the Japanese differ more distinctly. In the number of 

 teeth of the antennal scale the typical form is intermediate (5); the 

 West Atlantic form varies in one direction (6 to 7), while the Pacific 

 varies in the other: the Hawaiian with 3 to 5 teeth is more closely 

 allied to the typical form than the Japanese, which has only 2 or 3 

 teeth. 



It is very likely that intermediate localities, when found, will tend 

 to connect these forms more closely, and it would be interesting; to 

 know particulars about these connecting links. 



