BROWNE— MEDUSA FROM THE INDIAN OCEAN 179 



tentacle, very close to the bulb ; it is a narrow band of dark pigment on the surface of 

 the ectoderm. 



One specimen is infested with Cunina buds in different stages of development. The 

 buds are attached to the sub-umbrella close to the base of the stomach. The largest 

 Cu7iina shows three rows of otoporpse on each lappet, and is about ready for 

 liberation. 



Bougainvillia fulva is widely distributed over the Pacific and Indian Oceans, and 

 lives within the tropical belt. 



Genus TuREiTOPSis, McCrady, 1857. 



There are differences of opinion amongst specialists on medusae as to the number 

 of species that should be recognised as belonging to the genus Turfitopsis. Mayer (1910) 

 and Bigelow (1913) clearly consider that the American Turritopsis nutricula, McCrady, 

 is identical with the European Titrritopsis polycirrlia, Keferstein. Maas (1909) is 

 practically of the same opinion, but he suggests that the species should be kept apart, 

 as local forms or varieties. Acting upon his own suggestion, Maas described a new 

 Turritopsis from Japan as a new variety of Turritopsis nutricula. 



Hartlaub (1911) on the other hand seems fairly convinced that the American and 

 European Turritop)sis belong to distinct species. I may here say that I agree with 

 Hartlaub in placing Turris neglecta, Lesson, as a synonym of Turritopsis polycirrlia. 

 Sometime before the appearance of Dr Hartlaub's publication I had already come 

 to the same conclusion. 



With regard to the medusa described by Maas (1909) under the name of Turritopsis 

 nutricula, var. pacifica from Japan, I think it should be regarded as a distinct species, 

 and under the name Turritopsis pacifica. Maas clearly states that the ocelli are abaxial, 

 that is to say, on the outer side (ex-umbrella side) of the basal bulbs, whereas both 

 Turritopsis nutricula and Turritopsis polycir'rha have their ocelli on the inner side 

 of the basal bulbs. Even if Maas, as Bigelow (1913) has hinted, has accidentally 

 recorded and figured the ocelli on the wrong side of the bulb, still, in my opinion, it 

 remains a distinct species. Maas's figures show that the formation of endoderm above 

 the stomach is similar to that of Turritopsis polycirrha, but it can be distinguished from 

 Turritopsis p)olycirrha by having a much larger number of tentacles (120 — 150) arranged 

 in several rows round the margin of the umbrella. 



Since I have seen the specimens of Turritopsis in the "Sealark" collection and 

 compared them with specimens of Turritopsis polycirrha from the English Channel and 

 the North Sea, I am strongly in favour of Hartlaub's views and believe the reasons given 

 by him for separating the American and European species are sound. 



In Turritopsis nutricula the radial canals, by a considerable thickening of their walls, 

 and coalescence, form a kind of endodermal peduncle upon which the stomach hangs. 



In Turritopsis polycirrha a further development of endoderm takes place. It is no 

 longer confined to the walls of the radial canals, but grows across the top of the umbrella 

 cavity and forms a homogeneous mass of cells. This extension also grows downwards and 

 takes in the radial canals in the uppermost part of the sub-umbrella. The extension 



23—2 



