﻿MARINE ASELLOTE ISOPODS — ^MENZIES 119 



that the omission of reference to this minute dorsal uropodal branch 

 lias been due to its being overlooked by the several researchers who 

 have worked on the genus, and that it will in all probability be found 

 on the other species belonging to the genus. Of course this makes the 

 differentiation of Munna from related genera a more difficult task, but 

 at the same time it indicates closer affinities. 



In three of the examined species a small but distinct squama was 

 detected on the third joint of the peduncle of the second antenna. 

 In a fourth species, M. ubiquita^ there was only a slight indication of 

 such a scale, in the form of a large seta. Reference to this observation, 

 like that concerning the dorsal uropodal branch, appears to be lacking 

 in the published description of species of Munna to which I have had 

 access, and this character appears to have been overlooked. The 

 squama also indicates a closer affinity between Munna and its related 

 genera. 



As mentioned, it is possible to divide Munna species into several 

 gToups, some of which may become recognized genera when M. hoeckii 

 is better known. The following attempt at a division of the genus, 

 while obviously incomplete, seems none the less worthwhile: 



A. Species having a leaf like, flattened, ventral uropodal branch 

 lacking spinelike protuberances. Each male first pleopod not ex- 

 panded laterally at apex, apex pointed. Gnathopods of adult male 

 and female specimens similar. Male third pleopod with terminal 

 joint of exopod not equal in width to width of terminal joint of endo- 

 pod. Probably includes Munna nana Nordenstam, Munna acanna 

 Miller, Munna petiti Amar, and Munna ubiquita, new species. 



B. Species having rounded (in X-section) ventral uropodal branch 

 bearing at least one large spinelike protuberance. Each male first 

 pleopod expanded laterally at apex. Gnathopods of adult male en- 

 larged and swollen, unlike those of adult females and subadult males. 

 Male third pleopod with terminal joint exceeding in width the width 

 of terminal joint of endopod. Probably includes Munna avatshensis 

 Gurjanova, M. kr^yeri Goodsir, M. yalmata G. O. Sars, M. stephenseni 

 Gurjanova, and M. chromatocephala^ new species. 



C. Species similar to those in B, except ventral uropodal branch ap- 

 pears to lack any large spinelike protuberance. A distinct, dorsal] y 

 visible, dentate, suburopodal shelf is present, which structure is lack- 

 ing in species mentioned in B. Probably includes Munna minuta 

 Hansen and Munna halei^ new species. 



D. Species lacking eyes. Minute structure of mouth parts, pleopods, 

 and uropods not known. Equals Coecimunna Richardson, 1908, and 

 includes Munna truncata Richardson and M. acanthifera Hansen. 



E. Species to which such assignments are impossible at the present 

 time, owing to their being inadequately known. Includes a vast 

 majority of the species. 



