MYSIDACEA— TATTERSALL. 293 



Telson about as long as the sixth, abdominal somite and one and a quarter tunes 

 as long as broad at the base, cleft for one quarter of its length ; cleft armed with two 

 long plumose setae, a short proximal portion of each lateral margin of the cleft 

 unarmed with teeth, the remainder of these margins with a dense row of closely set, 

 comb-like teeth ; lateral margins of the telson armed with about 16-18 spines 

 distributed throughout the whole length, the proximal three spines on each side 

 longer than the others, the distance between the terminal spine and the one proximal 

 to it greater than the distance between any other adjacent spines, terminal spine 

 about one-twelfth of the entire length of the telson. 



Inner uropod one and a third times as long as the telson, with a row of closely 

 set spines, about 32 in number, on the inner margin, the spines increasing in size 

 distally, the most distal spine situated a short distance from the apex of the uropod. 



Outer uropod one and three quarters of the length of the telson. 



Length of adult females, 10 mm. 



I have not seen males belonging to this species. 



Remarks. — This species is easily recognised by the extreme length of the antennal 

 scale, the peculiar shape of the frontal plate and the greatly set-back position of the 

 antero-lateral angles, and the form of the telson and uropods. The acute spine on 

 the mandibles may be regarded as an additional specific character. It is present on 

 all three specimens I have examined, and is probably characteristic of the species. I 

 have pleasure in naming the species after its discoverer, Professor C. Chilton, to 

 whose courtesy I am indebted for the opportunity of examining and describing it. 



15. Tenagomysis similis, sp. nov. (Plate II, figs. 9-13.) 



Occurrence.—'' Terra Nova," Bay of Islands, August 1912, numerous ; 

 " Terra Nova," Station 136, four ; Ocean Beach, collected by Crosby Smith, four 

 females, two males, 6-7 mm., from Professor Chilton ; Bay of Islands, two females, 

 5 mm. (recorded as T. novae-zealandme by Thomson, 1900), from Professor W. B. 

 Benham. 



Description.— C&Y&^Rce short, leaving the last three thoracic somites exposed, 

 produced in front to form a short triangular rostral plate with the apex acute, almost 

 spiniform ; antero-lateral angles produced into acute spines ; a prominent pseudo- 

 rostral process below the rostral plate and almost as long as the latter. 



Eyes not quite twice as long as broad, cornea hemispherical, occupying half the 

 eye in dorsal view. 



Antennal scale extending slightly beyond the distal end of the antennular 

 peduncle, three and a half times as long as broad, ovate-lanceolate in shape, setose 

 all round, terminal joint large, a prominent spine on the outer corner of the basal 

 joint from which the scale springs. 



Antemial peduncle extends to the level of the middle of the third joint of the 

 antennular peduncle. 



