ACT INI ARIA 



53 



Edwardsia vegae n. sp. 



Diagnosis: Physa weU-developed, perforated by apertures. Scapus with a rather well-developed 

 periderm, polygonal, with scattered, especially in the lower part large nemathybomes. Nematocysts of the 

 physa 14—19 fi, those of the nemathybomes 84—101 x 3 /^ those of the tentacles 19—24 x 2 //, those of 

 the actinopharynx 38—43 X 3 Z'- Tentacles 16. Longitudinal pennons of the mesenteries in the reproductive 

 region with about 25—30 strong folds which are rather high and richly ramificated in the outer part, low and 

 only sUghtly branched in the inner one. Outer lamellar part of the mesenteries attached to the pennon at 

 some distance from its outside. Parietal muscles with somewhat numerous, in the outer part closely packed 

 folds; in transverse-sections through the re- 



Textfig. 62. 



Edwardsia vegae. 



I/jn^ituciinal section of the involved 



physa and of part of the scapus (sc), 



en : endoderm, ec : ectoderm, 



a : annular wall. 



^■?SV<Rv 



productive tract folds trianguloid. Expansion 

 of the parietal muscles on the column? 



Colour in presen-ed state: Scapus 

 dirty-brown. 



Dimensions in strongly contracted 

 state with the physa and one part of the sca- 

 pus involved: Length 1.7 cm, largest breadth 

 about 0.5 cm. 



Occurrence: Arctic Sea of Siberia. 

 Off Pittlekaj North of the winter harbour of 

 the Vega 9 — 10 fms. stones (Vega-Exp. 1879, 

 No. 1002) I sp. 



Exterior aspect: The phj'sa is well- 

 developed, but involved. It is perforated by a 

 central aperture, surrounded by a ring of pro- 

 bably 8 apertures. The scapus is provided with 



8 distinct, longitudinal furrows and is thus polygonal. The nemathybomes are large, especially in the lower 

 part, scattered over the whole surface and distinctly discernible to the naked eye. The capitulum being 

 damaged, I cannot decide whether it is polygonal. The short tentacles are 16 in number. The actinopharynx 

 is short. As it was not well-preserved I cannot say whether a siphonoglyphe is present or not. 



Anatomical description: The ectoderm of the physa is very high, considerably thicker than its 

 mesogloea and provided with sparse nematocysts, 14 — 19 // long. On transverse-sections through the centre 

 of the phj'sa a central aperture is seen which is probably formed by an involution of the ectoderm (textfig. 

 62). From the aperture an annular wall {a), probably of ectoderm, extends into the coelenteric cavity. (Com- 

 pare Edwardsia vitrea) . By the side of the central aperture I have on certain sections observed apertures of 

 similar appearance. Accordingly there is probably a central aperture, surrounded by a ring of 8 apertures. 

 On the inner side of the apertures a distinct layer of circular muscles is developed as in Halcampa. The 

 scapus-ectoderm is thin, its periderm ordinarily developed, the mesogloea thick, probably on account of the 

 strong contraction of the body. The nemathybomes are large and contain, in addition to round cells, rather 



