Rev. Canon A. M. Norman on British Mysidse. 247 



Subfam. V. Mysin.e. 



Genus 8. Hemimysis, G. O. Sars, 1869. 



Carapace having part of one or one and part of a second 

 segment of cephalothorax exposed beliind. Eyes subglobose, 

 peduncles short. Antennal scale rather small, shortly lanceo- 

 late; outer margin more or less ciliated, no spine. Mouth- 

 organs generally resembling those of Mysis, but the mandibles 

 with second joint of palp expanded and subovate. Legs with 

 4-5-jointed tarsus, ending in a very slender spine-like nail. 

 Marsupial pouch formed of three pairs of lamina?, one of 

 which is very small. Pleopods in female small, rudimentary : 

 in male, two first pairs rudimentary, third with large basal 

 joint and one branch ; fourth very long, styliform, termin- 

 ating in two filaments ; fifth with large basal joint and two 

 multiarticulate, strongly ciliated branches adapted for 

 swimming. Telson not large, cleft at the extremity. Outer 

 uropods one-jointed, long and narrow, truncate at the extre- 

 mity, ciliated all round. 



The character of the pleopods in the male distinguishes this 

 from all other genera : while the fourth pair are very like the 

 same organ in Schistomysis ornata, the third and fifth pairs are 

 wholly ditferent ; these are formed for swimming and closely 

 resemble the same pairs in the genus Leptomysis. The female 

 may be distinguished from Mysis by the mandible-palp, the 

 short antennal scale, and slender nail of the perseopods. 



Hemimysis Lamornce (Couch). 



1856. Mysis Lamornce, Couch, ' The Zoologist,' p. 5286. 

 1860. Mysis Lamornce, Norman, Ann. & Mag. Nat. Hist. ser. 3, vol. vi. 

 pi, viii. figs. 4, 5. 



1863. Mysis Lamornce, Goes, Crust, decap. podoph. Sueciae, p. 15. 



1864. Mysis aurantia, G. O. Sars, Beret, omen i Somm. 1863 foretagen 

 Zool. Keise, ]3. 20. 



1879. Mysis Lamornce, G. O. Sars, Carcinol. Bidrag til Norges Fauna, 

 I. Monogr. Mysider, p. 65, pi. xxx. 



1882. Hemimysis potitica, Czerniavsky, I- c. fasc. i. p. 117, pi. vii. 

 fasc. iii. p. 48. 



1883. Mysis aurantia and Lamornce, Czerniavsky, /. c. fasc. iii. p. 54. 



General form short and robust, anterior portion of cepha- 

 lothorax as broad as or broader than earlier segments of 

 pleon ; colour bright red or orange. Eyes short but very 

 large, projected only slightly beyond margin of cephalothorax. 

 Rostrum very short, obtusely angulated. Antennules having 

 the peduncle robust, basal joint equal to the two following. 

 Antennal scale elongated-subovate, about three times as long 



