624 ABTHUR WILLEY. 



ill the integument of the trunks the occurrence of dorsal roots 

 putting the fibrous layer of the collar nerve-cord in connection 

 with the fibrous layer of the epidermis, and the presence of 

 liver saccules, and of synapticula between the branchial bars. 



Group IT, including the genera Schizocardium and Glan- 

 diceps, characterised by the presence of an inner layer of 

 circular muscles (inside the longitudinal layer), and by the 

 occurrence of a long vermiform process extending forwards 

 from the anterior end of the notochord or proboscis caecum.^ 



Group III, including the genus Balaiioglossus, charac- 

 terised by the absence of circular muscles in the integument 

 of the trunk, and by the absence of synapticula. 



Spengelia belongs to the second of the above groups, but 

 exhibits features which render it a remarkably synthetic 

 genus. 



The following table (compiled from Spengel) will suffice to 

 show the relation of Schizocardium and Glandiceps to one 

 another, and will assist in the appreciation of the characters 

 of Spengelia. 



Schizocardium. Glandiceps. 



1. Ventral septum of proboscis ex- Ventral septum of proboscis stops 



tends to anterior end of vermi- short at base of vermiform process 



form process of notochord. of notochord. 



2. Pericardial auricles well deve- Pericardial auricles rudimentary. 



loped. 



3. Peripharyngeal spaces present. Peripharyngeal spaces absent. 



4. Synapticula present. Synapticula absent. 



5. (Esophageal portion of branchial CEsophageal portion of branchial sac 



sac reduced. well developed. 



6. Liver saccules present. Liver saccules absent. 



7. Medial gonads absent. Medial gonads present. 



8. Anterior, unpaired, post-branchial Ditto. 



intestinal pores (Darmpforten) 

 present. 



1 It would be desirable to translate the German word " Eicheldarm " in 

 such a way as not to involve an abstruse morphological conception, which 

 some authors object to, 



