22 bulletin: museum of comparative zoology. 



in February and March, as will become clear through an inspection of 

 Kriinimel's Temperature Charts (Kettler's Zeitschrift, Bd. VI., Taf. II., 

 III. Also, Bull. Mus. Comp. Zool. at Harvard Coll., Vol. XIV., pp. 240, 

 242, Figs. IGS, 169). Unfortunately the Hydromedusan fauna of the 

 Gulf of Guinea is unknown, but when we come to know it, we would not 

 be surprised were it found that many Tortugas forms are established in 

 this region. 



Hie Scyphomedus(B of the Bahama-Tortugas region are, for the most 

 part, distinctly West Indian types, and are quite different from the 

 species found on the Atlantic Coast of Africa. It is well known that 

 these forms are much more abundant along coasts than they are in the 

 open sea. The Discomedusse, especially, are given to congregating in 

 swarms in bays and estuaries. We are therefore not surprised to find 

 that most of the Bahama-Tortugas species are peculiar to the West 

 Indies and the adjacent warm coasts of North and South America. 

 VanhofFen (1888 ; Bibliotheca Zoologica, and 1892 ; Acalephen der 

 Plankton Expedition) has given maps showing the geographical dis- 

 tribution of Scyphomedusse, and from an inspection of his charts it 

 becomes quite apparent how these forms are distributed along coasts, 

 and that few of them have yet been found in the open sea. Indeed, 

 according to Vanhoflfen ('92) only six Scyphomedusse were found by the 

 Plankton Expedition of 1889, which confined its investigations, as far 

 as possible, to the open sea far from coasts. 



The following Scyphomedusa; appear to be restricted to the Bahama- 

 Tortugas region and the West Indies : Cassiopea frondosa, Lamarck ; 

 Cassiopea xamacana, Bigelow ; Linerges mercurius, Haeckel ; Linergcs 

 pegasus, Haeckel ; Linuche ungiculata, Eschscholtz ; Linuche vesiculata, 

 Haeckel ; Aurelia habanensis, Mayer ; Aurelia marginalis, L. Agassiz ; 

 Charybdea xamacana, Conant ; Tripedalia cystophora, Conant ; Charyl)- 

 dea punctata. In addition to these the following forms are established 

 in the Bahama-Tortugas region, but extend also for a considerable 

 distance northward along the coast of the United States : Pelagia 

 cyanella, P^ron and Lesueur ; Dactyloraetra quinqnecirra, L. Agassiz ; 

 Tamoya haplonema, F. Mtiller. The following species extend from the 

 "West Indies southward along the Brazilian coast ; Dactylomctra lactca, 

 L. Agassiz ; Tamoya haplonema, F. Mtiller. 



There are also a few Scyphomedusre of very wide distribution that 

 are found in the region of the West Indies and Bahamas. Among 

 these are : Nausithoe punctata, Kolliker, found in the Mediterranean, 

 the Trojiical Atlantic, and the T^ahaiiias. A very close variety, N. 



