392 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 2 



Discussion. The genus Stephanostomum was named by Looss in 1899. 

 In accordance with the then accepted interpretation of the rules of nomen- 

 clature, Looss came to consider the name Stephanostomum unavailable 

 because of the generic name Stephanostoma Danielsen, 1880, and in 1901 

 he renamed the trematode genus to Stephanochasmus. Stephanochasmus 

 Looss, 1901 became the recognized name for the genus and has been and 

 still is the most commonly used term. 



However, a Recommendation under Article 36 of the International 

 Rules of Zoological Nomenclature reads: "It is well to avoid the intro- 

 duction of new generic names which dififer from generic names already 

 in use only in termination or in a slight variation in spelling which might 

 lead to confusion. But when once introduced, such names are not to be 

 rejected on this account." The first example cited is "Picus, Pica." In 

 Opinion 25 of the International Commission it was voted 11 to 1 (3 not 

 voting) that Damesella, 1905 should not be rejected because of the exist- 

 ence of Damesiella, 1898. 



Following this Recommendation, the writer (Manter, 1934, p. 286) 

 considered that Stephanostomum Looss, 1899 was "not to be rejected" 

 on account of its similarity to Stephanostoma. However, recommenda- 

 tions of the International Commission are not mandatory, and some 

 authorities might prefer to continue with the use of the name Stephano- 

 chasmus. 



Stephanostomum longisomum, new species 

 (Plate41,figs. 75, 76) 



Host: Caranx hippos (Linnaeus) 



Location : Intestine 



Localities: San Francisco, Ecuador 



White Friars, Mexico (type locality) 



Number: One specimen in each of 2 hosts examined. In both 

 cases, Stephanostomum megacephalum was also pres- 

 ent. 



The following diagnosis is based on one complete specimen and one 

 incomplete specimen lacking the forebody. The measurements (except 

 egg size) are on the complete specimen, although the fragment showed 

 similar proportions so far as could be seen. 



SPECIFIC DIAGNOSIS OF STEPHANOSTOMUM LONGISOMUM 



Length 7.627 ; width 0.540, most of hindbody about equally wide. 

 Forebody 0.937 or about y% total body length; posttesticular space 0.802. 



