Rev. Canon A. M. Norman on British Mysidse. 1G3 



Eri/iJn'ops serrata is at once distinguished from all other 

 British Mysidea by the serrations of the outer margin of the 

 antennal scale. A species, however, similar in this respect, 

 E. ahyssorum, G. 0. Sars, occurs in Norway, but is distin- 

 guished from it by the extraordinary length of the peraeopods, 

 the last pair of which when bent backwards reaches beyond the 

 uropods ; by the greater production of the apex of the antennal 

 scale, which considerably overtops the point of distal spine- 

 process of outer margin ; by the extremity of the telson not 

 being truncated in a straight line, but slightly arcuated ; and 

 the inner margin of the inner uropods not being serrulated. 



Genus 6. Mysidopsis, G. O. Sars. 



Eyes large, subglobose, somewhat flattened ; pigment dark 

 coloured. Antennal scale lanceolate, setose all round. 

 Maxillipeds 5-articulated, gnathopods 6-articulated and very 

 robust, both ending in a nail. Ze^ssubequal ; tarsus 4-articu- 

 lated, and shorter than preceding joint, ending in a slender 

 nail. Telson hollowed above, of moderate size, sides spined, 

 extremity truncated or cleft (cleft simple, that is, not serrated) . 

 Pleopods in female less narrow than usual, lateral basal dila- 

 tation small ; in male well developed, with multiarticulate 

 swimming-branches ; fourth pair with outer swimming- 

 branch terminating in a single spine-like seta, densely ciliated 

 at the extremity ; last pair having, besides tlie narrow lateral 

 basal lobe on the inner branch, a conical projection ending in 

 a single seta. Uropods, inner with large acoustic organ, the 

 spines of its inner margin confined to the neighbourhood of 

 the acoustic organ j outei- broader than usual. 



1. Mysidopsis didelpliys (Norman). 



1803. Mysis didelphys, Norman, Trans. Tyneside Nat. Field-Chib, 

 vol. V. J). 270, pi. xii. figs. 9-11. 



1804. Mysidopsis didelphys, G. O. Sars, Beretning om en i Sommeren 

 1803 foretagen Zool. Reise i Christiania Stift, p. 27. 



ISeO. Mysidopsis didelphys, Normau, " Last Report Dredging Shet- 

 land," Brit. Assoc. Rep. for 18n8, p. 207. 



1872. Mysidopsis didelphys, G. O. Sars, Monogr. Mysider, ii. p. 20, 

 pi. vii. 



1883. Mysidopsis didelphys, Czerniavsky, /. c. fasc. iii. p. 24. 



Body robust. Sides of cephalothorax converging gradu- 

 ally forwards into a broadly triangular short rostrum, with 

 acute apex, which extends rather more tiian half the length 

 of the first joint of the peduncle of the antennules. Antennal 

 scale narrowly elongate-ovate, about one third longer than the 



