DESCRIPTIONS OF GENERA AND SPECIES 



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■with Kynotus in having a spermiducal gland. Tykonus agrees with Kynotus in the 

 fact that the setae do not commence until about the seventeenth segment, and in 

 the presence of a 'bursa.' On the other hand, the Old -World genus, Microchaeta, is 

 unique among the Old- World genera in having lateral nephridiopores. This genus 

 is regarded by E.OSA as being intermediate between his two siibfamilies. 



Among the Acanthodrilidae and other earthworms, the number and position of the 

 contractile hearts are of systematic importance ; the position of these varies also in 

 the Geoscolicidae. As a rule the last pair are placed more anteriorly than is the 

 case with the Acanthodrilidae or the Perichaetidae ; in the genus Ilyogenia, for 

 example, the last pair of these commissural vessels are in the eleventh segment. 

 Unfortunately, the blood-vessels have not been studied in a considerable number of 

 Geoscolicidae ; we know, however, the position of the hearts in the following genera : — 

 The last pair of hearts in the genus Pontoscolex is in segment xii. 



