NO. 6 gilbert: three new trematodes 101 



SPECIFIC DIAGNOSIS OF CETIOSACCUS GALAPAGENSIS 



(Measurement in mm.) 



This species has the following characters in addition to those 

 mentioned above: size 7 to 13 by 1 to 1.3. Oral sucker 0.30 to 0.42 

 in diameter. Esophagus short, ceca narrow, twisted posteriorly, end- 

 ing separately. Testes separated by a short distance. Cirrus sac 

 spherical containing a male genital papilla projecting into a terminal 

 chamber; ovary separated from anterior testis by a short distance; 

 shell gland posterior to ovary, with enclosing membrane; vitellaria 

 lateral just anterior to ovary, about twenty-seven follicles on each 

 side; metraterm extending posterior to cirrus sac; eggs 19 to 23 by 

 9 to 11 jx. Host: Amblyrhynchus cristatus. 



The genus name Cetiosaccus is from cetio (monstrous) and 

 saccus (vesicle) referring to the very large excretory vesicle. The 

 species name galapagensis is for the locality. 



Comparisons. The only closely related genus is Teloporia with 

 which Cetiosaccus agrees in its simple ceca, shape and position of 

 the testes and ovary, lack of seminal receptacle, its median genital 

 pore and egg shape. But Cetiosaccus differs very widely from Telo- 

 poria in many respects, especially: the excretory system with its 

 glandular vesicle and united crura; the spherical cirrus sac and pe- 

 culiar genital papilla; and the compactly coiled seminal vesicle of 

 two regions. 



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