956 REPORT OF COMMISSIONER OF FISH AND FISBERIES. [30] 



tral mouth. Its lower walls are not muscular. The cavity is a simple 

 one, and was not observed to send out radial jiouches from its periphery. 



The velarium {vel ) is a collar-shaped structure hanging from the mar- 

 gin of the umbrella, from which position its walls are probaly vertically 

 placed. It is a thin-walled flexible body, crossed by vertical bands {per.) 

 (peronise), which in one or two instances bind together adjacent marginal 

 lapi^ets. Its free lower edge is poorly preserved in all specimens studied ; 

 but in one specimen a structure, which may be true velum, was imper- 

 fectly seen. !No sense bodies were observed, although they probably 

 exist, and may be looked for on the free margin of the velarium in living 

 specamens. Tentacles are very long, placed at the line of union of the 

 velum and the outer rim of the umbrella. They are inserted at the 

 proximal end of the peronia^, and as a consequence, in those specimens 

 in which the marginal lappets are formed by the breaking up of the 

 velarium, the point of insertion of the tentacle is at the base of the 

 cleft formed by the rui)ture. The tentacles are firmly connected with 

 the free margin of the velarium by means of the peroniae, and are 

 joined to the walls of the umbrella by a conical root {pero.) which pene- 

 trates the substance of the umbrella. Each basal root or means of 

 union of the tentacle and the disk lies in the same radius as the eleva- 

 tion {col. sub.) on the subumbral side of the disk which separates two 

 radial furrows {fos. rad.). The radial elevations are therefore similar 

 in position to the tentacular socles of Atolla. 



The sexual glands were not observed. These bodies, so necessary to 

 distinguish the two genera Solmaris and Solmoneta Haeck. from each 

 other, are in all cases wanting. 



The function of the radial elevations or their corresponding depres- 

 sions on the under surface of the umbrella is not known. Similar ele- 

 vations have been described in Atolla, Collaspis, Nauphantopsis, and 

 other genera on the exumbrella, but are not known to exist or are very 

 rare in other medusae, especially of the Hydroida. An approach in 

 structure to them which can be mentioned among true hydroid gono- 

 phores are the radial rows of small tubercles which I have figured on the 

 subumbral surface of the bell of Polycanna {Zygodactyla) Grcenlandica. 

 ^hese structures can hardly be said to be homologous in the two cases. 

 A radical difierence between the Trachy medusae and Narcomedusae and 

 the Acraspeda has been thought to be the absence of a velum in the 

 latter, and its development in the former. I think in Solmaris we have 

 a genus indicating that the homologue of the velum is to be looked for 

 among the Acraspeda in the marginal lappets. 



It has been stated by Haeckel that in the genus Solmaris the tentacle 

 and peronia are in reality continuous, so that the true insertion of the 

 tentacle is at the extremity of the peronia on the free border of the wall 

 of the velarium. It is true that the i^eronia is an appendix of the ten- 

 tacular base, but that the proximal extremity of the tentacle lies at 

 the margin of the umbrella, near its union with the vertical wall of the 



