. Bulletin of the Natural History Museum Zoology. DEEP-SEA PROTOBRANCHIA (BIVALVIA) 127. Fig. 41. Propeleda carpenteri. External lateral views of the right sides of two small shells to show differences in shape from the specimen illustrated in text-figure 40. Specimens taken from Atlantis II station 239 from the Argentine Basin. Scale = I mm. The concentric ridges on the shell of the present specimens while not particularly marked are more so than those described by Dall, though the syntypes that we have examined are dead valves that are somewhat worn (). Our specimens also are very slig
. Bulletin of the Natural History Museum Zoology. DEEP-SEA PROTOBRANCHIA (BIVALVIA) 127. Fig. 41. Propeleda carpenteri. External lateral views of the right sides of two small shells to show differences in shape from the specimen illustrated in text-figure 40. Specimens taken from Atlantis II station 239 from the Argentine Basin. Scale = I mm. The concentric ridges on the shell of the present specimens while not particularly marked are more so than those described by Dall, though the syntypes that we have examined are dead valves that are somewhat worn (). Our specimens also are very slightly more anteriorly extended than the syntypes, though the characteristic antero-dorsal curvature of the shell margin is the same. Our speci- mens correspond well with the figures given by James (1972, figs 67 and 68). These latter come are from similar depths (2340-2627m) to some of our own. It would appear that specimens from mid to lower slope differ slightly from those taken at shallower depths however, we regard the differences as being at most infrasubspecific. There is a marked change in shape during growth. Juveniles are much shorter than the adults and subsequent growth involves in- creasing elongation of the post-umbonal shell. The prodissoconch is extremely large measuring 630um in length. Internal morphology () The adductor muscles are oval in cross-section, the posterior being the more fusiform, both are set some distance in from the shell margin. The posterior adductor muscle lies opposite the limit of the posterior hinge plate, the anterior muscle is attached to the shell just dorsal of the mid-horizontal shell axis. The siphonal embayment is elongate, the siphons are slender and entire. The anterior sense organ is small in size. The foot lies in the anterior half of the mantle cavity in preserved specimens, it is relatively elongate and has numerous small papillae present along the margins of the sole. The palps are small, each bearing an extremely long,
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