MYSIDACEA— TATTERSALL. 281 



four females, tliree males ; Station 133, one male, three females ; Station 135, about 

 twenty ; Station 136, one male, two females. 



I have also examined specimens, kindly sent to me by Professor Chilton, from 

 Hawkes Bay (coll. Hutchinson) and Ocean Beach (coll. Crosby Smith). 



Remarks. — This material enables me to supplement Thomson's description, and to 

 indicate the position of the species in relation to other Pacific forms. It belongs to 

 Hansen's Group 1, but departs in some few points from his definition of this group. 

 It, however, agrees with this group in the characters of the male pleopods and their 

 pseudobranchial rami, and is thereby excluded from all the other groups. A brief 

 description may be useful. 



Frontal plate of the carapace only slightly produced into a broad, low triangular 

 projection, of which the apex is bluntly pointed and its angle somewhat greater than 

 a right angle. Beneath the frontal plate is a prominent pseudo-rostral process, which 

 projects beyond the rostral plate. Eyes of moderate size, pigment black. Antennular 

 peduncle with the first joint larger than the combined second and third. Antennal 

 peduncle equal in length to the first joint of the antennular. Antennal scale equal in 

 length to the antennular peduncle, three times as long as broad, outer margin terminated 

 by a strong spine, beyond which the terminal lobe of the scale extends. Thoracic limbs 

 stout, tarsus of the endopods two- jointed, the first joint short. 



Last abdominal somite twice as long as the fifth. Telson one-third longer than 

 the sixth abdominal somite, and equal in length to the proximal joint of the outer 

 uropod, three times as long as broad at the base, proximal widened portion with from 

 three to five strong spines on each side, distal part of the lateral margins having from 

 fifteen to twenty spines, the proximal ones arranged regularly and increasing regularly 

 in size, the distal ones arranged in two or tluree series of graded spines, apex of the telson 

 with a single pair of prominent spines, between which are three equal spinules and a 

 pair of plumose setae. Outer uropod one and a half times as long as the telson, proximal 

 joint twice as long as the distal joint, its outer margin armed distally with from nine 

 to eleven stout spines, which occupy slightly less than the distal half of the margin, 

 distal joint twice as long as broad. Inner uropod extending half way between the apex 

 of the telson and the tip of the outer uropod, its inner margin furnished with thirteen to 

 seventeen spines extending from the statocyst to the tip. 



Pseudobranchial rami of the first and fifth pleopods of the male straight, those of 

 the second, third and fourth pleopods spirally twisted. Terminal setae of the third 

 and fourth male pleopods unmodified. Males with a well- developed hirsute lobe on 

 the antennules. Length of adult specimens of both sexes, 11 mm. 



Among the species belonging to Hansen's Group 1, S. denticulata is distinguished 

 by the greater length of the armed portion of the outer margin of the proximal 

 joint of the outer uropods and the larger number of spines foimd there. It also 

 has a greater number of stout spines on the proximal wider portion of the telson 

 than any other of this group. It appears to be closely related to S. watasei, Nakazawa, 



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