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i. Pedicellina compacta n. sp. (PI. II, figs 13, 14). 



293. B. Stat. 273. Anchorage off Pulu Jedan, Aru Islands, 13 Metres; sand and shells (on 

 293. A., Adeonelld). 



Total length about 660 u., the stalk not much longer than the calyx. Tentacles about 

 12. Stalk relatively thick, uniform in diameter or diminishing towards the calyx; without spines. 

 Stolon-branches given off freely from the bases of the stalks, one or two usually present, on 

 each side, in this position. Sexes apparently separate. 



The specific name refers to the comparatively thick and short stalk; though the con- 

 dition shown in figs 13 and 14 is no doubt that of contracted specimens. A diminution in 

 size of the stalk at its distal end, often observable, doubtless indicates that this part is less 

 contracted than the more proximal portion. 



I have found this species only once, on a species of Adeonella, which in some parts 

 is profusely covered with it. The general character of the stolon is identical with that of other 

 species, a barren part alternatiug with a stalk-bearing portion. A chitinous diaphragm passes 

 across the stolon at no great distance from the base of a stalk ; and this is equally true of the 

 main stolon and of its lateral branches. The crowded arrangement of the individuals of the 

 colony is due partly to the fact that the barren stolon-segments are short, and partly to the fact 

 that lateral stolon-branches are given off very freely, as shown in fig. 14, where two are present 

 on each side. In individuals in which I have been able to count the tentacles, the number has 

 been 1 2 ; and I regard this as the typical number. In some cases, as in the specimen show in 

 fig. 13, the rectum has an erect position. I think that this condition is associated with the 

 development of a brood-pouch from the floor of the vestibule, since in young calyces in which 

 there is no brood-pouch the rectum is recumbent on the wall of the stomach. The gonads seem 

 to be female in all the individuals in which they can be made out; and this appears to indicate 

 that the sexes are separate and that all the specimens mounted belong to a female colony. 



The measurements (in p.) of the individual represented in fig. 13 are: — length of 

 calyx, 300 ; of stalk, 360 ; total length, 660 ; breadth of calyx, 230; of stalk, 60 — 70. 



The majority of the known species of Pedicellinidae belong to the genus Barentsia ; 

 and there are comparatively few which fall within Pedicellina s. str. Of these, the form which 

 most nearly resembles the present species in general appearance is P. australis, described by 

 Ridley l ) from Sandy Point, Straits of Magellan, 7 — 10 fathoms. With this species it agrees 

 in the number of tentacles ("about 12"), but differs from it in size; the measurements given 

 by Ridley for his species including the following : — total length 2.5 mm., calyx 1 mm. 

 I have verified these measurements from the type slide (79. 12. 27.36) in the British Museum, 

 although I find that the total length, 2.5 mm., is obtained by including the breadth of the 

 stolon-segment from which the stalk arises. It thus appears that the calyx alone of Ridley's 

 species is longer than the total length of the 'Siboga' form: and the difference in size is so 

 marked that it seems impossible to refer the 'Siboga' species to P. australis. 



1) Ridley, S. O., 1881, "Zool. Coll. 'Alert'". I'roc. Zool. Soc, p. 60. Pedicellina australis Jullien, is a Barentsia\ see the 

 account of B. discreta in the present Report, p. 29. 



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