388 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 2 



Locality: Cerros Island, Mexico 

 Number: 5 specimens 



This species is a common trematode at Tortugas, Florida, where 

 Manter (1933) has reported it from 14 different hosts. It has not been 

 recorded elsewhere. Thus, this extension of a Gulf of Mexico form to the 

 Pacific is of special interest. Until recently, only two Helicometrina spe- 

 cies (//. nimia and H. parva) have been known, but Srivastava (1936) 

 has described H. septorchis and H. orientalis from the Bay of Bengal. 



Manter (1933) considered Helicometrina azumae Layman, 1930 in 

 the genus Rhagorchis Manter, 1931; Yamaguti (1934) considered H. 

 azumae in his new genus Decemtestis. The chief difference between Rha- 

 gorchis and Decemtestis seems to be the presence of an external seminal 

 vesicle in the former. Since no external seminal vesicle was described for 

 H. azumae, Yamaguti's disposition seems to be correct, and Rhagorchis 

 azumae (Layman, 1930) Manter, 1933 becomes a synonym of Decem- 

 testis azumae (Layman, 1930) Yamaguti, 1934. 



Labrifer secundus, new species 

 (Plate 40, fig. 70) 

 Host: Pimelometopon pulchcr (Ayres) 

 Location : Intestine 

 Locality: Cerros Island, Mexico 

 Number : One from a single host 



This single specimen occurred with another trematode {Lepocrea- 

 dium bimarinum). The posterior end was torn away or macerated but all 

 other organs were clearly discernible. The unique structure of the acetab- 

 ulum and the peculiar male genital organs very clearly indicate the genus 

 Labrifer in which, to date, but one other species is known. Therefore, 

 since generic and specific identification is easily possible, the species is de- 

 scribed in spite of the small quantity of material. 



SPECIFIC DIAGNOSIS OF LABRIFER SECUNDUS 



Body smooth, with rapidly tapering forebody and rounded anterior 

 end, pigment spots in forebody. Body fragment (probably nearly com- 

 plete) 1.35 by 0.690 with greatest width at acetabular level. Oral sucker 

 subterminal 0.150 in transverse diameter, with transverse aperture; ace- 

 tabulum 0.412 in diameter, weak, deeply embedded in body, its aperture 

 small, transverse, guarded by an anterior and posterior lip of homogene- 

 ous structure and by larger lips (anterior and posterior) with parallel 



