. Bulletin of the British Museum (Natural History). THE DISTRIBUTION OF PELAGIC POLYCHAETES 391 Description. No complete specimens of this species were collected ; the longest head-fragment is 15 mm. in length. Treadwell's original material does not appear to have been complete, the first twenty-one segments measuring 8 mm. The proboscis has two long terminal processes, each carrying a pair of basal ailerons between which there are no papillae. There are three pairs of small tentacular cirri, one on each of successive segments behind the head ; the first of these pairs is the largest and joine
. Bulletin of the British Museum (Natural History). THE DISTRIBUTION OF PELAGIC POLYCHAETES 391 Description. No complete specimens of this species were collected ; the longest head-fragment is 15 mm. in length. Treadwell's original material does not appear to have been complete, the first twenty-one segments measuring 8 mm. The proboscis has two long terminal processes, each carrying a pair of basal ailerons between which there are no papillae. There are three pairs of small tentacular cirri, one on each of successive segments behind the head ; the first of these pairs is the largest and joined ventrally by basal ceratophores ; the second and third are equal in size. There are only four antennae, all on the anterior border of the pro- stomium arranged in dorsal and ventral pairs ; of these the ventral pair is sharply pointed and noticeably the longer, being always at least twice as long as the blunt dorsal pair. No median unpaired antenna is present in this species : on the top of the prostomium, between the eyes (where the unpaired antenna is present in all other species of Vanadis) there is a pronounced crest but this cannot be called an antenna. The anterior seven pairs of parapodia are achaetous with very small cirri ; thereafter parapodia are fully developed ; chaetae are long and compound, cirri ovate, and the pedal lobe carries a cirriform appendage. In mature females 10 Vanadis minuta : lateral view of head and extruded proboscis of specimen from Stn. 63 of the Northern Hohday Expedition. the dorsal cirri of the second parapodia are modified as receptacula seminis. None of the specimens examined has the pigmented segmental glands preserved suffi- ciently well to allow accurate examination. Discussion. Dales (1957) was the first to record V. minuta after its original discovery ; I have examined some of his specimens in the () collections, and they are identical in all respects with those described here including having four antennae. In suggesti
Size: 3285px × 761px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., 1962, boo, bookauthorbritishmuseumnaturalhistory, bookcentury1900
