4 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.61. 



Type species. — Allacanthochasmus varius, new species. 



ALLACANTHOCHASMUS VARIUS. new species. 



Plate 1 and text figures 1 and 2. 



Diagnosis.— With the characters of the genus. Body length of 

 mature worms variable from 0.58 to 2.4 mm. Relation of body length 

 to diameter subject to great range due to states of contraction. Diam- 



. mouth 

 -oral epino 

 -oral suckei' 



- pbarynx 



mmMmmm 







--seminal veaiole 



-- vltollaria 



-- gsnital orlfico 



— acetabulvim 



. --reoeptaoulum 

 eemlnla 



ovary 



teatia 



Fig. 2.— Details of structure of Allacanthochasmus vabius. The uterus is com- 

 pletely FILLED WITH EGRS, BUT FOR CONVENIENCE IN THIS DRAWING IS SHOWN IN FLAT 

 stippling. VITELLAKIA OF DORSAL INTERCECAL REGION HAVE BEEN OMITTED, AS HAVE 

 ALSO THE CUTICULAU SPINES. THE SCALE .ACCOMPANYING THIS DRAWING HAS THE RELA- 

 TIVE VALUE OF 0.1 MM. 



eter of crown of spines around mouth about 0.18 to 0.25 mm. Indi- 

 vidual spines of oral circle usually about 41[;. long though they fre- 

 quently range from 35 to SSfx. Usually 24 spines in the oral circle 

 though in some instances a smaller number has been observed and in 

 one individual 28 were present. Oral sucker 0.150 to 0.240 mm. 

 across at widest part. Pharynx located directly posterior to oral 

 sucker and at its posterior margin giving rise to the bifurcated intes- 



