458 Wetmore, Developme7H of the Stomach in Euphonias. [oct. 



THE DEVELOPMENT OF THE STOMACH IN THE EU- 

 PHONIAS. 



BY ALEX. WETMORE. 



The stomach of the small brightly colored Tanagers known as 

 Euphonias has long been noted as one of the most anomalous in the 

 avian group, but to my knowledge no explanation for its peculiari- 

 ties has been attempted. During recent field work in Porto Rico 

 for the Biological Survey, and in subsequent laboratory investiga- 

 tions, it has been my fortune to examine critically 51 specimens of 

 the Porto Rican Euphonia ( Tanagra sclateri) and on these examina- 

 tions the following observations are based. 



In the long array of species forming the order Passeriformes the 

 stomach is composed ordinarily of two parts ; a smaller, constricted 

 glandular portion, the proventriculus, connected with the oesopha- 

 gus, and a larger, more or less muscular division the ventriculus, 

 which opens into the duodenum by the constricted pyloric orifice. 

 In the Euphonias, however, a different development is encountered. 

 The glandular proventriculus is large and well developed while 

 the stomach proper is indicated by a thin, transparent, membra- 

 nous band or zone which passes over without lessening in size into 

 the dilated end of the small intestine, lined internally with project- 

 ing villi. In addition the passage from the oesophagus down is 

 direct, without apparent cardio-pyloric flexure, a combination of 

 peculiarities that stamps this group of species as unique among their 

 feathered kindred. 



Attention was drawn to the intestinal tract of the Euphonias by 

 Lund in 1829 but he was misled into describing a lateral diverti- 

 culum of the zonary portion, which he considered as the rudimen- 

 tary ventriculus. For fifty years his discussion and plates were 

 quoted and reproduced by other zoologists so that they are found 

 in many of the standard texts published during that period. The 

 eminent English ornithotomist W. A. Forbes reviewed these facts 

 before the Zoological Society of London in 1880, disproving the 

 presence of Lund's ventricular diverticulum, but was unable to 

 assign any reason for the aberrant structure which he found. 



