380 SYNOPTIC COLLECTION. 



In speaking of segments Mr. Scudder says, 1 "The 

 entire body [of Peripatus] is of a leathery texture with no 



external signs of segments The same is true when 



the internal structure of the body is examined, for neither 

 in the disposition of the muscles nor of the tracheal ap- 

 paratus does it appear that one could judge whether a 

 pair of legs represented one or more segments of the 

 body ; even in the nervous system it is only indicated 

 by a small ganglionic swelling next each pair of legs. 

 The tracheae are like extended cutaneous glands, inde- 

 pendent of one another and scattered over the body, and 

 the longitudinal muscles show no segmental breaks." 

 This weakness of segmental divisions is evidence of spe- 

 cialization by reduction, and we therefore place Peripatus 

 among those forms that have become more or less modi- 

 fied from the ancestral type by the suppression of certain 

 characters, such as distinct segmentation of the body 

 and distinctly jointed legs. We have already pointed 

 out many cases, especially among parasites, where there 

 is a marked weakness in segmentation. 



Peripatus when disturbed secretes a quantity of slime, 

 the slime glands opening at the end of the oral papillae. 

 The mouth is encircled by a lip which is raised into 

 papillae, and these adhere to the food while the jaws 

 probably tear it in pieces. 



The different species of Peripatus are determined in 

 part by the number of paired walking-legs, Peripatus 

 capensis (PI. 940, fig. i ; fig. 3, leg enlarged) having 

 seventeen pairs and Peripatus edwardsi (No. 939) having 

 from twenty-nine to thirty-four pairs. These legs are 

 similar in function and therefore in structure. They are 

 obscurely jointed ; 2 and since Peripatus lives in damp 



1 Mem. Boston Soc. Nat. Hist., Ill, no. 9, 1884, p. 287. 



2 Scudder, Amer. Journ. Sci., (3), XXIV, 1882, p. 166, says, 

 legs "obscurely jointed, the joints being perceptible only at the 

 extreme tip and on the apical half of the inner side." 



