70 BULLETIN 201, UNITED STATES NATIONAL MUSEUM 



several hundreds. The Johnson-Smithsonian expedition is repre- 

 sented by three localities : Gangway at Santa Barbara, Samana Bay, 

 Dominican Republic (series number 310B), surface, February 17, 

 1923, 5 specimens; anchorage off Playa de Fajardo, Puerto Rico, series 

 number 358A, surface, February 23, 1933, 10 plus specimens ; Luispena 

 Channel, Puerto Rico, series number 406, February 25, 1933, 10 

 specimens. 



Distribution. — The species is evidently a very abundant one in the 

 tropical parts of the western Atlantic. It is not an oceanic species 

 but it frequents waters near land, either among the islands of the 

 Caribbean Sea or near the mainland. May and June seem to be its 

 breeding season, for nearly all the females recorded above had either 

 eggs or embryos in the marsupium. 



Remarks. — On May 7, 1937, 1 described this species under the name 

 Siriella occidentalis from specimens collected by the Johnson- 

 Smithsonian expedition in 1933 in the Caribbean Sea. Earlier in 

 the same year a paper appeared by Coifmann describing a new 

 species of Siriella under the name S. chierchiae, which was collected 

 on a journey from Pernambuco to Rio de Janeiro. The date of Coif- 

 mann's paper is March 1937. I think there can be no doubt that 

 S. chierchiae and S. occidentalis are synonymous. It is true that Coif- 

 mann makes no mention of the modified third pleopods of the male, 

 but in all other characters the resemblance is so close as to leave no 

 doubt as to the identity of the two forms. Since Coifmann's paper 

 has priority, the species must be known as S. chierchiae and the name 

 S. occidentalis must be canceled. 



The species is very closely related to the other American species, 

 /S. pacifica, S. roosevelti, and S. panamensis, and can be identified with 

 certainty only from the examination of adult males. All four species 

 have both the third and fourth pleopods of the male modified and in 

 this respect differ from all other species except S. anomala, from which 

 all can be distinguished by the pseudobranchial rami of the male 

 pleopods, which are not spirally twisted in S. anomala. 



SIRIELLA PACIFICA Holmes 



FlGTJBE 17 



Siriella pacifica Holmes, 1900, p. 227. — Hansen, 1913b, p. 175, pi. 9, figs. la-f. — 

 Tatteksall, 1932a, p. 302. 



Description. — For the sake of completeness I give here a transcrip- 

 tion of Hansen's redescription of this species. The species belongs to 

 the second group of Hansen's classification, for the definition of which 

 see under S. chierchiae, and within this group may be defined as 

 follows : 



