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ENTEE.OPNEUSTA FROM THE SOUTH PACIFIC, 



peripharyngeal spaces separate, vestigial or absent ; perihaemal cavities contain transverse 

 muscles ; the layer of circular muscles in the body-wall lies inside of the longi- 

 tudinal muscles ; genital pleurae and lateral septa, absent ; external liver-saccules 

 present or absent. 



A. Right and left peripharyngeal cavities present ; synapticula present. 



Genus 1. SCHIZOCARDIUM, Spengel. 



Ventral septum of proboscis extends to end of vermiform process ; external liver- 

 saccules present ; medial gonads absent ; pericardial auricles highly developed ; oesophageal 

 portion of branchial sac reduced to narrow hypobranchial band. 



S. brasiliense, Spengel. S. peruvianum, Spengel. 



Genus 2. SPENGELIA, Willey. 



Ventral septum of proboscis does not extend to the vermiform process ; external 

 liver-saccules absent ; medial gonads present or absent ; pericardial auricles reduced ; 

 dermal pits in the genital region ; oesophageal portion of branchial sac present as a 

 deep groove. 



S. porosa, Willey. S. alba, n. sp. 



B. No peripharyngeal cavities and no synapticula. 



Genus 3. GLANDICEPS, Spengel. 



Ventral septum of proboscis, external liver-saccules and medial gonads, as in 

 Spengelia ; pericardial auricles rudimentary ; oesophageal portion of branchial sac 

 reduced to a broad hypobranchial tract. 



G. talaboti (Marion), G. hacksi (Marion), G. ahyssicola, Spengel. 



Family III. BALANOGLOSSIDAE n. n. 



It is not easy to define this family in terms similar to those employed in the 

 definitions of the two preceding families, because the anatomical characteristics are 

 chiefly of a negative nature. 



The most important properties of the members of this family may be summed 

 up as follows: — Boreal forms; with large eggs; developing directly (i.e. without a 

 pelagic larva). 



Stomochord without vermiform process ; roots absent ; cornua of nuchal skeleton, 

 efferent vessels of proboscis and perihaemal cavities, as in Spengelidae ; peripharyngeal 

 spaces present or absent ; no circular muscles in body-wall of trunk-region ; synapticula 

 absent ; external liver-saccules absent. 



