2 NATURAL HISTORY BULLETIN. 



from British waters, and the very striking white colour of the 

 hydranths, a feature not found in any other Eudendrium in 

 that locality. Eudendrium album is one of the most abundant 

 hydroids at Plymouth during the spring, where it has here- 

 tofore been regarded as Eudendrium capillare Alder. It 

 seemed, however, so different from the descriptions and 

 figures of that species given by Alder, Hincks, and Allman, 

 that specimens were sent to the veteran authority on hydroids 

 — Professor Allman — who regarded it as probably new, and 

 advised the writer to describe it as such. 



Clytea johnstoni Alder. Medusae of this species were 

 produced in the aquaria in May. 



Obelia geniculata Linn. Numbers of the medusae of 

 this species were bred in the tanks and bottles of the Labora- 

 tory during the latter part of April. They may be readily 

 distinguished from the medusae of Obelia dichotoma, which is 

 very abundant at Plymouth, by the fact that the former have 

 24 marginal tentacles, while the latter has but 16 at the time 

 of liberation. These small medusae are readily preserved 

 with the tentacles well expanded by stupefying with cocaine 

 and passing through three or four grades of alcohol. 



Obelia longissima Pallas? A specimen brought to the 

 Laboratory early in April is referred with some doubt to this 

 species, which it closely resembled in all respects, except in 

 the fact that the hydrothecae were marked with regular longi- 

 tudinal flutings, the ridges between the adjacent hollows 

 terminating in blunt teeth at the margin. This beautiful 

 ornamentation was quite constant in the hydrothecae, and 

 formed so striking a feature as to suggest a new species. 

 The close agreement, however, of the specimen with Hincks' 

 description and figures of O. longissima, taken together with 

 the great delicacy of the hydrothecae of the latter, render it 

 probable that the form under consideration was O. longissima, 

 with the delicate hydrothecae shrunken so as to be thrown 

 into longitudinal flutings. The gonosome was not present. 



Secured in Millbay Channel from a depth of about eighteen 

 fathoms. 



