360 



HYDROID^. 



Part IV. 



JE. purpurea Per. and LeS. ; M.-Ediv., in Cuv. Regn. An. Zooph., 

 PI. 43, fig. 3. — Polyxenia purpurea Esch. — New-Holland, En- 

 dracht (Peron and LeSueur).^ 

 Crematostoma A. Ag? 



C. flava A. Ag? — Gidf of Georgia, W. T. (A. Agassiz). 



Mesonema pileus Less., PI. 6, fig. 1, belongs to this genus. 

 Melicerta Less^ 



M. morchella Less., PI. 6, fig. 4. — Geryonie morille, PI. 6, fig. 4. 

 Oriaiin unlinown. 

 Mesonema Esch. 



M. Coelum pensile Esch. — M. coerulescens Koll. — Medusa Forsk., 

 Tab. 28, B. — iEquorea mesonema. Per. and LeS. — ^quorea 

 Rissoana DelleCh., PI. 73, figs. 1 and 2. — Mediterranean (Forskal). 



M. macrodactylum Br., PL 4. — Pacific, Equator (Mertens). 



M. abbreviata Esch., PI. 11, fig. 3. — Sunda (Eschscholtz). 

 Zygodactyla Br. — Rhacostoma Agass. 



Z. coerulescens Br. — Mesonema coerulescens Br., PI. 5. — Pacific 

 Ocean, Lai. 35° K, Long. 144° W. (Mertens). 



Z. dubia Ag. — Mesonema dubium Br., PI. 26. — Conception Bag and 

 Coast of Chili (Mertens). 



Z. groeulandica Ag. — ^quorea groenlandica Per. and LeS. — Me- 

 dusa ^quorea Fah. — Medusa globularis Mod. — Rhacostoma 

 atlanticum Ag. — Greenland (Fabricius); Coast of Maine, Bag of 

 Fiindy, and Massachusetts Bag (Agassiz). 



^ Judging from the figure of LeSueur, published 

 by Milne-Edwards, this species belongs to a differ- 

 ent genus. 



^ Crematostoma A. Ag. Digestive cavity hanging 

 down below tlie level of the circular tube ; lips of 

 actinostome large, lanceolate, fimbriated, and as nu- 

 merous as the chymiferous tubes, of which there 

 are from sixty to eighty. One large marginal ten- 

 tacle opposite the base of each of the chymiferous 

 tubes, without intermediate ones. 



' Crematostoma flava A. Ag. Spherosome very 

 heavy, of a slight blueish tinge. Chymiferous tubes 

 broad, extending down the projection of the disk 

 into the cavity of the bell. Tentacles with a 

 broad base, dark yellow, as well as the chymif- 

 erous tubes ; the ovaries extend from the circular 



tube to the base of the digestive cavity. The 

 digestive cavity is almost colorless, but the lips of 

 the actinostome are of the same color as the base 

 of the tentacles. Ratio of actinal to polar diam- 

 eter as three to one and three quarters ; from three 

 to four inches in diameter. — Gulf of Georgia, Wash- 

 ington Territory (A. Agassiz). 



^ The name Melicerta or Melicertum has been 

 applied to two very different genera, among Aca- 

 lephs. It is to be retained for the type to which 

 Medusa campanula Fabr. belongs, and for which 

 Lesson proposed the name Campanella, unfortu- 

 nately already preoccupied ; see p. 349. Melicerta 

 Less, must be changed, but I forbear to do it, as 

 this Medusa is little known. Melicerta Perla Per. 

 and LeS. seems to be a young Pelagia. 



