NO. 3 fraser: hydroids 131 



Distribution 



Ninety-nine species are listed from these four expeditions, of which 

 all but 20 have been reported in one of the other papers. Of the 20, 

 twelve are described as new. In the three papers, 213 species have been 

 listed, 94 of them new. 



The proportions of the numbers in the three main areas — A, oceanic 

 islands, 29; B, mainland coast, south of Balboa, 46; C, mainland coast, 

 north of Balboa, 56 — have been changed somewhat, mainly because of 

 the extension of the exploration area southward, to include Peru, as in 

 Area B there is a greater proportionate number. 



Forty-two species have not been reported outside this area. The dis- 

 tribution of the other 57 shows a marked parallelism to the distribution 

 of those reported in the 1934 paper. 



1934: South of Area B, 13 species, 13% ; North of Area C, 52 species, 

 52%; North Atlantic, 77 species, 77%; 1932, 1933, 1935, 1938; South 

 of Area B, 9 species, 15.8%; North of Area C, 31 species, 54.4%?; 

 North Atlantic, 43 species, 75.4%. 



It is significant that even when the coast of Peru is included, there 

 is still little affinity to the hydroids of the coast of Chile. The Humboldt 

 Current must make a very definite demarcation. As far as hydroid dis- 

 tribution is concerned, there is nothing like it anywhere in the northeast 

 Pacific. 



Species and Distribution 



Family Glavidae 



Turritopsis nutricula McCrady. — Chacahua Bay, 5-10 fathoms. 



Family Atractylidae 



Bimeria gracilis Clark.— Bahia Honda, 3-5 fathoms; Parker Bay, 30 



fathoms. 

 Bimeria vestita Wright.— Manta Bay, shore; Pinas Bay, 30-35 fathoms; 



Panama, shore; White Friars, 15-20 fathoms. 

 BougainviUia crassa Fraser. — Panama, shore. 

 Perigonimus gracilis Fraser. — Octavia Bay, 35-40 fathoms. 

 Perigonimus repens Wright. — South and east of Daphne Major Island, 



55 fathoms; Octavia Bay, 35-40 fathoms; Chacahua Bay, 5-10 



fathoms. 

 Perigonimus robustus Fraser.— Black Rock, south of Cape Corrientes, 



5-10 fathoms. 



