REVISION OF RECENT BAIRDIIDAE 31 



graceful slender hook; copiilatory organ with distal part large and 

 swollen, perforated by copulatory tube and carrying small dorso- 

 distal seta. 



Material. — Nosy Be; one living male, 100 subfossil specimens. 



Dimensions.— Adult male USNAI 121271, left valve, length 0.80 

 mm, height 0.45 mm; right valve, length 0.79 mm, height 0.41 mm. 



Subfossil distribution. — Fairly common in shallow carbonate 

 sands, especially near reefs, at Nosy Be, Madagascar. 



Affinities. — The carapace of this species seems very similar to 

 that illustrated by Miiller (1894) for Bairdia corpulenfa Miiller, 

 reported from the Bay of Naples and Marseilles regions, and it is 

 possible that the Nosy Be form is a subspecies of the Mediterranean 

 species. However, Miiller states that both sexes of B. corpulenta lack 

 the bifid hook on the distal antennal claw and have only one ventral 

 seta of branchial plate of first thoracic leg segregated and strengthened. 

 These anomalous characters, combined with the different termination 

 of the copulatory organ, suggest sufficient distinction to justify sepa- 

 rating the Nosy Be form as a new species. 



Neonesidea parilihamata, new species 



Figure 11 



Etymology. — Latin parilis, equal + hamatus, hooked. 



Type specimens. — -Holotype adult male USNM 121273; allotype 

 female USNM 121274; paratypes USNM 121275-121276. 



Type locality. — Nosy Be, Madagascar, sample 045 (washings of 

 a dead coral fragment overgrown with a tunicate, three sponges, 

 and annelid worm burrows, among patch reefs just below low tide 

 level at Ambariobe). 



Diagnosis. — Carapace small, smooth, swollen, ventrally flattened, 

 lateral outline approaching rhomboidal, muscle-scar pattern elongated 

 diagonally to 4 linear aggregates, inner lamella brown, posteroventral 

 margin of left valve finely denticulate, all other margins smooth. 



Distal antennal claw of male with both points of hook slender and of 

 equal size, female ^nth smoothly tapering claw having tiny anterior 

 barb; distal part of copulatory organ very long, lamellar, curved, 

 bearing a conspicuous seta distally; penetrated at midlength by 

 pointed tip of triangular copulatory tube support. 



Material. — Nosy Be; 8 living specimens, 12 fossil specimens. 



Dimensions.— Adult male USNM 121273, left valve, length 0.61 

 mm, height 0.36 mm; right valve length 0.60 mm, height 0.38 mm. 



Adult female USNM 121274, left valve, length 0.63 mm, height 

 0.37 mm; right valve, length 0.62 mm, height 0.35 mm. 



Habitat. — Nosy Be; crawling on sponges, corals, and other sessile 

 invertebrates just below low tide level at Ambariobe. 



