NO. 1 DAWSON : MARINE RED ALGAE OF PACIFIC MEXICO 77 



Type : Holotype is Coker 59, in the Herbarium of the New York 

 Botanical Garden, 



Type locality: At a depth of 5 meters, Isla San Lorenzo, Peru. 



Mexican distribution: Pacific Baja Calif. — D. 8593, Isla 

 Guadalupe, Dec. (tetrasporic and cystocarpic). Jalisco — D. 3733, Barra 

 de Navidad, Dec. (cystocarpic). 



The tetrasporic plants from Isla Guadalupe appear to be identical 

 in details of habit, morphology and anatomy with the species described 

 by Howe and attributed to southern California by Hollenberg. Two 

 cystocarpic plants in this material and several in the Jalisco collection 

 show the plant to be a Pterocladiaj as the arrangement of the rhizoidal 

 filaments also would suggest. Although it will be necessary to obtain 

 Peruvian material in the cystocarpic phase for positive confirmation of 

 the present transfer, the close correspondence of the tetrasporangial plants 

 of the Mexican and Peruvian collections seems to justify the action. 



Taylor's Pterocladia musciformis from Costa Rica, to judge from the 

 habit and tetrasporic reproduction, appears to be a closely related species 

 differing in its subcylindrical basal rhizomes and dissimilar branching. 

 Its position in Pterocladia has not been verified by the discovery of cysto- 

 carps. 



The plant from Monterey, California figured as Gelidium calogloss- 

 oides by Smith, 1945, pi. 44, figs. 3-4, has decidedly pinnate erect parts 

 unlike either the Mexican or Peruvian specimens and is in this respect 

 more suggestive of the species described below as Pterocladia parva. 



Pterocladia parva sp. nov. 

 Plate 6, fig. 2 



Thallis parvis, uno usque etiam compluribus ramis, erectis vel re- 

 pentibus, e partibus rhizomatiformibus subteretis vel compressis minor- 

 ibus quam 200 fi diametro, ope paxillorum parvorum vel discorum fixis ; 

 ramis erectis, liberis ad 15 mm. longis, supra complanatis, 300-500 /a 

 latis, semel vel bis irregulariter pinnatis, pinnis interdum valde confertis ; 

 filamentis rhizoideis aggregatis intra zonam meduUarem angustam; 

 cystocarpis prope terminos ramularum liberarum. 



Thalli small, growing on shells and crustose corallines on rock sur- 

 faces, consisting of subterete or compressed rhizome-like creeping parts 

 from which arise suberect, free branches ; creeping branches less than 200 

 ju, wide, fastened at frequent intervals by a peg- or disc-like attachment, 

 giving rise from these nodes to one or several free branches some of which 

 may become determinate, repent and attached; indeterminate free 



