REVISION OF RECENT BAIRDIIDAE 51 



SuBFOSSiL DISTRIBUTION. — Nosj Be, moderately common in car- 

 bonate beach, reef, and platform sands. 



Dimensions.— Adult male USNM 121299, left valve, length 0.75 

 mm, height 0.46 mm; right valve, length 0.76 mm, height 0.40 mm. 



Adult female USNM 121300, left valve, length 0.86 mm, height 

 0.53 mm; right valve, length 0.83 mm, height 0.42 mm. 



Paranesidea spongicola, new species 



Figures 25-26; Plate 1: figures 9, 10 



Etymology. — Latin spongia, sponge + -cola, dweller. 



Type specimens. — Adult male holotype USNM 121302; allotype 

 USNM 121303; paratypes USNM 121304-121305. 



Type locality. — Washings of dead coral and shell fragments 

 from coral patch reef talus at Pointe Lokobe, Nosy Be, Madagascar 

 (sample 373). 



Diagnosis. — Carapace with highly arched dorsum, left valve 

 approximately symmetrical in lateral view, greatest height located 

 midlength, greatest thickness located at midheight, exterior abun- 

 dantly covered with distinct circular pits, largest in median area. 



Copulatory organ with simple lobate terminal part bearing 1 or 2 

 vestigial projections, copulatory tube strong and gently arched. 



Material. — Nosy Be, 17 living specimens 433 subfossil specimens. 



Comores: one male living at LK-39, Mayotte I. 



Habitat. — Nosy Be, sporadically encountered in a great variety 

 of shallow-water epifaunal niches, crawling on algae, dead coral 

 fragments, living corals and sponges, in the reef and back-reef zones. 



Subfossil distribution. — Nosy Be, abundant and nearly ubiq- 

 uitous in shallow-water sediments, especially reef-derived sands. 



Dimensions. — Adult male specimen USNM 121302, left valve, 

 length 0.82 mm, height 0.54 mm; right valve, length 0.81 mm, height, 

 0.48 mm. 



Adult female USNM 121303, left valve, length 0.91 mm, height 

 0.63 mm; right valve, length 0.87 mm, height 0.53 mm. 



Affinities. — This is an extremely common morphologic type, and 

 forms with similar carapaces are found in most shallow-water tropical 

 assemblages. 



Paranesidea ? cheroconcha, new species 

 Figure 27c, d, i 



Etymology. — Greek cher, hedgehog +^oncAe, shell. 

 Type specimens. — Holotype adult female specimen USNM 

 121306; paratypes USNM 121307-121308. 

 Type locality. — Anton Brunn cruise 7 station 372P. 



