32 
PACIFIC SCIENCE, Vol. XXI, January 1967 
Fig. 22. Loxoconcha sp. a-c, Specimen usnm 648775; a, dorsal view of right valve showing postero- 
lateral sulcus; b, lateral view showing pustulose surface, Mn0 2 obscuring posteroventral area; c, internal view. 
Loxoconcha longispina Keij, 1953 
Figs. 23 a-d 
Loxoconcha alata Brady, 1880. Rept. Voyage 
Challenger, Zool. 1, pt. 3, p. 122, pi. 27, 
figs. 6 a-j. 
Loxoconcha alata longispina Keij, 1953. 
Koninkl. Nederl. Akad. van Wetenschappen, 
Amsterdam, ser. B, vol. 56, pt. 2, p. 160, pi. 1. 
diagnosis: Short rhomboidal carapace; well- 
developed ventral tubercle ; faint central sulcus ; 
pronounced reticulate ornamentation. 
description: In lateral view: carapace short, 
rhomboidal; dorsal margin straight, parallel to 
straight ventral margin; anterior margin evenly 
rounded but flattened in anterodorsum ; pointed 
caudal process in upper half of posterior mar- 
gin ; broad subcentral tubercle and faint post- 
adjacent median sulcus present; large pointed 
tuberculate alae ventrally extended; broad post- 
erodorsal enlargement sometimes developed. 
Eye tubercles large ; ornamentation of deep 
reticulations, elongate on ventral knob, small 
on subcentral tubercle. In dorsal view: carapace 
much wider than high due to massive posteriorly 
pointing knobs; posterior laterally compressed. 
Hingement gonglyodont: anterior element of 
right valve a rounded socket with postadjacent 
round tooth and small socket; sockets connected 
above tooth ; median element a crenulate groove, 
coarser at ends; posterior element a large pro- 
jecting reniform tooth; strong accommodation 
groove above median element of left valve. 
Adductor muscle scar pattern a row of four 
smaller equant scars on side of pit; large single 
antennal scar anterior to top two adductor 
scars; large conspicuous mandibular scar dor- 
sal to adductor group on median ridge. Con- 
tinuous flange and large groove around anterior- 
ventral -posterior duplicature of right valve; left 
valve with corresponding well developed sel- 
vage. 
