HYDROIDA II 



21 



again, we find in the shape of the hydrotheca; according to Kramp, (1911 p. 376) the margin of the 

 hydrotheca in Grammaria abictina - - in contrast to Grammaria immersa always curves outwards 

 slightly; in forma bre-vicyatha, on the other hand, this is only quite exceptionally the case, and by far 

 the greater number of hydrothecse show no indication of outward curvature in the margin. Kramp 

 has (1. c.) pointed out another feature which is here of more importance. In forma brcvicyatha, the 

 hydrotheca aperture is almost invariably turned somewhat obliquely upwards, not as in forma typica, 

 where the plane of the aperture is parallel with the axis of the branch, or in Grammaria immersa, 



.'0 



too in. 



. boom 



._ 1000 m. 2000 m. 



Fig. VI. Localities of Grammaria abietina (forma brevicyatha +) in the Northern Atlantic. 

 In the hatched region the literature notes a common, although scattered occurrence. 



where the opening is even turned slightly downwards. In forma brevicyatha, only the few large hydro- 

 thecse have a plane of aperture parallel with the axis of the branch. 



Grammaria abietina is a typical arctic-boreal species, recorded also in a single instance (Bil- 

 lard, 1904 p. 164) from the north of France. It may at times penetrate down to great depths, as for 

 instance at the "Ingolf" St. 92, where it reached 976 fathoms, the greatest depth hitherto recorded for 

 this species. Otherwise it is chiefly found (see fig. VI) in the deeper parts of the littoral regions of the boreal 

 and arctic area. Grammaria abietina is also apparently an Atlantic species; it is known from the east coast 

 of North America, to Taimur, but has not hitherto been recorded from about Bering Strait or the 

 Pacific. If, however, it should prove correct that Grammaria scandens Stechow is a synonym for 

 Grammaria abietina, then it must be classed among the circumpolar species. 



