258 S- H. BCXTON, 



tions of Peripatus (specimens given by Dr. Alexander Petrunke- 

 viTCH and Dr. M. Grabham of Jamaica), I was astonished to find 

 that they threw a great deal of light upon the reasons for these 

 differences in the coxal glands of the Arachnids. 



Perlpcttns, 



Specimens examined : 



P. juUformis. Male (Petrunkevitch, fixed in sublimate). 



P. jamaicensis. Female (Petrunkevitch, fixed in sublimate). 



P. juUformis and P. jamaicensis (Geabham, preserved in formol). 



All of the above were collected in Jamaica and in addition I 

 have examined three adult females containing embryos, of P. 

 nicaraguensis var. isthmicola (Bouvier) collected by myself in Costa 

 Rica and fixed in Duboscq's solution. 



Peripatus has a vai'iable number of legs, ranging from sixteen 

 in the Australian species to about forty in P. jamaicensis, and in 

 front of the legs are two segments; the jaws, corresponding to the 

 chelicerae, and the oral papillae, corresponding to the palps of the 

 Arachnids. The antennae, corresponding possibly to the rostrum of 

 the Arachnids arise from the pre-oral segment (Sedgwick) and are 

 not here considered to have any segmental value. 



On each of the leg bearing segments of Peripatus there is a 

 nephridium; the first five and the last three of which, irrespective 

 of the number of legs, are modified from type. Thirty legs is the 

 usual number for the American species and in describing the 

 nephridia it will be convenient to take the number of legs as thirty, 

 and the segments therefore as thirty-two. The genital segment near 

 the posterior end has no nephridium, but the posterior segments 

 have no bearing on the present argument, so for the sake of brevity 

 the genital segment will be disregarded. 



The typical nephridium found on segments eight to twenty-nine 

 possesses a saccule {8) from which a funnel bearing collecting tubule 

 [CT) leads into the labyrinth (CL) with its striated cells and 

 nuclei in the usual position (photos 47, 47a) but the striatiou is not 

 so clearly marked as in the Arachnids. The diagram E indicates 

 roughly the way in which the labyrinth coils and finally enters 

 the vesicle, but for a short distance at the loop (Lilf, of diagram 

 and photographs), the lining cells take on a totally difterent 

 character. The striation is lost and the nuclei lie at the base of 



