20 U.S. NATIONAL MUSEUM BULLETIN 29 5 



Ecology. — Species of Neonesidea are confined to rather shallow 

 water (less than 100 m). They are characteristic members of epifaimal 

 assemblages on marine algae, grasses, sponges, and, to a lesser extent, 

 detrital accumulations and associated sandy sediments. While they are 

 extremely abundant in reef and platform habitats just below low tide 

 level, they are not known to occur in the littoral zone at Nosy Be. 

 Subfossil carapaces are chiefly present in shallow-water sands, espe- 

 cially abundant near reefs or other environments where found living. 



Distribution.^ — Worldwide, chiefly in tropical and subtropical 

 areas. 



Affinities. — The species included in this genus may be further ar- 

 ranged into three smaller groups, typified by the species A^. schulzi 

 (Hartmann), A^. dinochelata (Kornicker), and N. pateriformis , new 

 species, and distinguished especially by carapace shape and muscle- 

 scar pattern. Within the A^. schulzi group fall most of the species 

 described by Miiller (1894) as well as N. gierlqffi, (Hartmann), N. gerda 

 (Benson and Coleman), N. phlegeri (McKenzie and Swain), and the 

 new species A^. antonhruuna, N. cracenticlavula, and N. aduncicorpu- 

 lenta. The A", dinochelata group includes A^. parilihamata, new species, 

 and other species that are at present either undescribed or known from 

 carapaces only, such as A^^. woodwardiana (Brady) and perhaps forms 

 identified as B. crosskeiana Brady by Puri (1960) and B. amygdaloides 

 Brady by Brady (1890); the most interesting feature of this group is 

 the fusion of muscle scars yielding a zigzag ahgnment of four wedge- 

 shaped scars. Finally, two extremely compressed forms A\dth nearly 

 oval lateral outline, A^. tenera (Brady) and N. paterijormis, new 

 species, seem sufficiently distinctive to represent a third potential 

 subgenus. Yet another category might be added either here or within 

 Paranesidea for such species as Bairdia serrata Miiller, 1894, Bairdia 

 roquebrunensis Rome, 1942, and "Genus Uncertain species 1" of this 

 paper, which combine appendage characters of Neonesidea with the 

 marginal spinosity and high-arched dorsal outline of Paranesidea. 



Neonesidea schulzi (Hartmann), 1964 

 Neonesidea schulzi schulzi (Hartmann), 1964 



Figures 4o-d, 5, 6 



Triebelina schulzi Hartmann, 1964, p. 44, pis. 4, 5: figs. 14-22. 

 Species BA, Maddocks, 1966, p. 47, fig. 22. 



Diagnosis. — Carapace elongate-ovate and streamlined in lateral 

 view; anterior margin of left valve without denticles, of right valve 

 with 3 to 5 short curved spines at about midheight; postero ventral 

 margin of right valve with about 15 tiny denticles, posteriormost 5 or 

 6 fused together as a platelet, left valve with about 15 denticles and a 



