﻿118 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 102 



of isopods, made by John Davis, which was deposited in the Univer- 

 sity of California collections and subsequently lent me for study. 

 To these gentlemen I extend my sincere thanks for their kind as- 

 sistance. 



Family MUNNIDAE 



(Cf. Nierstrasz and Schuurmans Stekhoven, Jr., 1930, p. X, e 108) 

 Genus MUNNA Kroyer, 1839 



Munna Kk0yek, Naturh. Tidsskr., vol. 2, p. 612, 1839. (Genotype, Munna boeckii 

 Kr0yer, 1839.) 



Generic diagnosis. — In general the generic diagnosis is modified 

 after G. O. Sars (1897-99, p. 106). Body subpyriform, with dorsal 

 surface somewhat vaulted; last three peraeonal somites small, with 

 lateral parts directed somewhat posteriorly. Cephalon usually broad. 

 Pleotelson consisting of two somites : A narrow, short, anterior somite 

 and a pyriform last somite. Eyes distinct (G. O. Sars, 1897-99) or 

 lacking (H. J. Hansen, 1916, p. 34). First antenna with a 3-jointed 

 peduncle and a flagellum composed of only a few joints. Second 

 antenna with a 6- jointed peduncle and a multiarticulate flagellum. 

 Mandible with a well-developed molar process, palp 3-jointed. Maxil- 

 liped with a 5- jointed palp. Gnathopods of adult male subchelate, 

 often enlarged and swollen. Remaining peraeopods ambulatory, not 

 subchelate, increasing in length, with carpal and propodal joints much 

 elongated and bordered with spinelike 2-pointed setae ; dactylar joint 

 small, biunguiculate. Uropods with one (?) or two branches. 



Remarks. — Even today this genus remains inadequately understood 

 and contains a vast number of species. The genotype, Munna hoeckii^ 

 is still imperfectly known, especially in respect to the minute structure 

 of the mouth parts, uropods, and pleopods. For that reason the di- 

 agnosis here given is very liberal, and I believe that once the genotype 

 is better known it will be possible to divide the genus into at least 

 two, and perhaps more, very distinct genera. It has been possible to 

 detect on the species that I have examined a minute but clearly dis- 

 cernible dorsal (outer) uropodal branch, which usually has but a 

 single seta at its apex, and which generally is concealed partly or totally 

 by the edge of the pleotelson. This is a rather significant observation, 

 in that the genus Munna has long been considered different from the 

 other genera belonging to the family Munnidae in lacking biramous 

 uropoda, e. g., "uropoda very small, simple" (G. O. Sars, 1897-99, p. 

 106) ; "uropoda small, simple" (Richardson, 1905, p. 480) ; "mit 

 kurzen eingliedrigen uropoden" (Vanhoffen, 1914, p. 561) ; "uropoden 

 einastig" Nierstrasz and Schuurmans Stekhoven, Jr. (1930, p. X, e 

 108) ; "uropoder enkla" (Hult, 1937, p. 9) ; et cetera.^ It is believed 



1 After the preparation of this paper, Dr. Raymond Amar (1948) discovered an additional 

 uropodal branch In Munna petiti Amar. 



