5i2 EiOHAtiD EVANS. 



by Professor Lankester many years ago in two species of tlie 

 genus Tubif ex (11). In this Annelid genus the tails of the 

 spermatozoa project freely from the wall of the spermato- 

 pliore, and are found in the living state in continual vibration. 

 In Eoperipatus the tails were not observed to project freely 

 from the body of the spermatophore, but it must be remem- 

 bered that it was not examined in the fresh state. If it were 

 examined fresh, it is quite possible that the tails of the 

 spermatozoa would be found to project freely into the cavity 

 of the duct. In the spermatophore of Eoperipatus as in 

 that of Tubif ex the spermatozoa are arranged radially round 

 a central core, which is free of them, as was figured in 

 Tubif ex by Professor Lankester (11). It is evident that 

 the spermatophore of Eoperipatus is but little in advance 

 of that found in the Annelid Tubifex. The next stage in 

 the evolutionary series is found in the genera Peripatus 

 and Peripatoides, where both the head and the body of 

 the spermatophore are provided with a horny coat (7) (16). 

 The genus Peripatopsis would supply a still further stage 

 in the series ; a stage in which the long spermatophore 

 of the other genera has been broken up, and is represented 

 by a number of small oval bodies each consisting of a thin 

 case full of spermatozoa (15). The last stage would be 

 represented by the condition of things found in Para- 

 peripatus, where the male genital ducts are described by 

 Willey as "containing abundant loose felted spermatozoa" 

 (18). 



If, on the one hand, the above account represents cor- 

 rectly the phylogenetic history of the spermatophore in the 

 Peripatida3, and if, on the other hand, as Willey seems to 

 think (18), the presence or absence of a long unpaired duct 

 is in correlation with the formation of a long spermatophore, 

 it seems that there are good reasons for doubting the con- 

 clusion that the condition of the genital ducts in the genus 

 Paraperipatus is primitive, though on a priori grounds it 

 appears to be so. This explanation of the features presented 

 to us enables us to place the Malay and Neotropical genera 



