1903] Eeport on some Medusae from Norway and Spitzbergen. 25 



incomplete. The type specimen shows all the important characters 

 possessed by the specimens in this collection and I believe that it 

 is identical with Pectyllis arctica of Haeckel. 



Haeckel has piaced his Pectyllidae consisting of three genera 

 and three species, namely Pectyllis arctica, Pectis antarctica and 

 Pectanthis asteroides, as a snb-family of the Trachynemidae (Tra- 

 chomedusae) and gives the folio w definition for the genus Pectyllis. 



"Trachynemidae with eight genitalia in the course of the eight 

 radial canals, without eentripetal canals. The genitalia are cut in 

 two by eight radial mesogonia or leaf-shaped mesenterial bands and 

 connected with the basis of the stomach. Oral eavity without oral 

 funnels and without side pouches. Tentacles with sucking cups 

 Tery numerous and piaced closely one over the other in several 

 rows on the umbrella margin. Numerous (8 or 16?) auditory clubs." 



The species (Pectyllis arctica) is described from specimens in 

 the Copenhagen Museum collected on the west coast of Greenland. 

 As there is only a single species in this genus the specific charac- 

 ters nearly correspond to the generic characters given above, but 

 further details are given. "Border of the umbrella thickened, 

 thickly beset with several rows of sucking cups, which are divided 

 into 16 larger and 18 smaller groups (16—20 sucking cups in each 

 group). Between them are piaced 16 longer and 32 shorter ten- 

 tacles .... The entire margin of the umbrella is continuously 

 beset with numerous tentacles (above a thousand), which are piaced 

 one over the other in several rows and are transformed into short- 

 stalked sucking cups . . . Only a small number of them appear 

 in the form of longer or shorter filaments; in the greater number 

 the filament part of the tentacle is so much reduced and the ter- 

 minal sucking-cup so strongly developed, that they appear as short 

 stalked or even unstalked suckers ("acetabula"; ... It was not so 

 easy, unfortunately, to determine the number of the longer tentacles 

 with a small sucking cup at the end, as most of them had been 

 torn away . . . The velum is very broad and powerful, and appears 

 capable of completely closing the umbrella eavity . . . The sub- 

 umbrella has also very strong circular muscles forming numerous 

 ring-like folds on the lower surface of the umbrella. The umbrella- 

 cavity is divided into eight deep funnel-like sections, as eight broad, 

 vertical, septa (4 perradial and 4 interradial) stretch across from 

 the eight radial canals and genitalia to the base of the stomach . . . 

 The central mouth leads into a tube-shaped quadrangular stomach, 



