62 



VERTEBRATE ZOOLOGY 



the base of the proboscis to the too-small neck of the same individual. 

 The space between the collar and the neck in front is like the ventral 

 mouth of Balanoglossus. Earth scooped in by this mouth is passed 

 rapidly through the alimentary tract and is deposited on the surface 

 by the anus. Digging in this way the animal quickly disappears 

 from view. 



Fig. 35. — Various types of Enteropneusta, relatives of Balanoglossus. K. 

 Balanoglossus clavigerus; B. Glandiceps hacksi; C. Schizocardiuin brasiliense; 

 D. Dolichoglossus koiDalevskii; a, anus; ab, alidominal and caudal regions; b, 

 branchial region; c, collar; g, genital region; gp, gill pore or branchial cleft; gii 

 genital wing; h, hepatic region; m, jiosition of mouth; p, proboscis; t, trunk. (From 

 riarmer; A, B, and C, after .Spengel; D, after Bateson.) 



There are about thirty species of Enteropneusta, grouped into nine 

 genera. Their mode of life is essentially the same as that of the genus 

 Balanoglossus. The other genera differ mainly in the relative impor- 

 tance and size of the three body regions, in the shape of these regions, 



