Observations on British Zoophytes. 317 



inches and a half. The number of lips of the latter was 

 about forty, the radiating canals, each having a long ovisac? 

 about eighty, and the marginal tentacles, by estimation, 

 four hundred. On examining the ovaries, I found that the 

 eggs were hatched, and the young, in the form of almost 

 invisible planuke, were issuing from the ovisacs. These 

 were gently extracted with a glass syringe, an instrument 

 so useful to those who practise the obstetric art amongst the 

 hydroidae, and were placed about three weeks ago in glass 

 tanks of clean sea-water prepared for their reception. Many 

 thousands of larvae were placed in the tanks, and of those, 

 about a score have been developed into Campanularian 

 polyps ; about a hundred are still progressing to that end, 

 and the rest have disappeared. It was with no little 

 impatience and anxiety that I saw the Planula during a 

 fortnight fix itself to the glass, spread itself out into a short 

 thread, secrete its scleroderm, put forth its polyp-bud — this 

 last slowly swelling day by day, until at last it opened, 

 and a polyp appeared, furnished with twelve alternating- 

 tentacles, joined together for about one-third of their length 

 by a web, the polyp enclosed in a cell terminating in many 

 acuminate segments. It is now about six years ago that I 

 was watching, in like manner, the slow evolution of a bud 

 from a Campanularian Zoophyte, the Laomedea acuminata 

 of Alder — the Campanulina of Van Beneden — the bud 

 opened, and a bright green medusoid issued forth, having 

 four lips and two tentacles. The polyp form of JEquoria 

 vitrina is, as far as I can determine, identical with that of 

 L. acuminata in shape ; but is so excessively small — quite 

 invisible to the naked eye — that we must wait for further 

 development before we can determine their identity. Ge- 

 ganbaur has proved that the Medusoid of Yelella acquires a 

 further number of canals and tentacles ; and I have else- 

 where recorded the successive changes which occur in the 

 Medusoids of several species of Atractylis. It is also certain 

 that such increase in the number of elements does occur in 

 JEquoria vitrina, for the smaller specimens have always a 

 less number than the larger. Meantime, the question as to 

 the larval state of JEquoria vitrina is settled. This, the 



