372 



PROF. W. J. DAKIN ON THE 



neigiiboiii'hood of the eyes. He recognises in certain Peripatus 

 species what is termed an ocular ring of papilh.e, with pai-t of it 

 (lifterentiatecl to form a frontal organ. In otliers he states : — 

 " Tarceau oculaire s'atteniie, puis disparait assez brusqnenieiit 

 apres avoir decrit iin pen plus d'un demitour, mais a ce niveau 

 ou menie bien plus en dedans, I'arceau infra-oculaire prend une 

 remarquable predominance, forme parfois un organe frontal et se- 

 continue par I'arceau spiral." The northern variety (Bouvier's 

 Peripatoides inoochoardi) is supposed to be one of the forms most 

 typical of this group of species. 



Several specimens of both varieties have been examined, and, 

 so far as can be made out, there is no difference greater than the 

 variations met with in either variety, between the two forms. 



The Legs. 



The number of legs appears to be very definite in the West 

 Austialian Peripatoides, and no variations are to be recorded 

 amongst the individuals from any one area. There is, however, 

 a marked difference between the two varieties Avhich irdiabit the 

 northern and southern areas respectively. 



]3ouvier stated that Peripatoides gilesii resembled P. suteri and 

 differed from all the other Australian Peripatoides in the possession 

 of 16 pairs of legs. At the same time it was stated to differ 

 from P. suteri in only having three pedal papi]]^e, in which respect 

 it agreed with other Peripatoides. 



Fletcher diagnosed the southern variety, P. occideoilalis, as 

 possessing 15 pairs of walking-legs, but no further description 

 was given. This is the difference between our two vaileties, 

 and it is most constant. All the specimens from Mundaring, 

 Armadale, Kelmscott, etc , in the north, have 16 pairs of legs, 

 whatever l)e their size or sex. All the southern specimens 

 bear only 15 pairs of legs. All the legs are similar with the 

 exception of the 4th and 5th pairs in both varieties, from 

 which one may conclude perhaps that it is one of the [posterior 

 pairs that is missing in the southern type. 



Each leg is marked by rings bearing papillae, but near the 

 apex on the ventral surface these papillae have united to form 

 spinous pads, the middle one of which is somewhat wider than 

 the others. Now in the northern variety the 4th and 5th pairs 

 of legs differ from the others in the fact that the proximal spinous 

 pad is segmented, a small central segment being cut off from 

 two larger lateral lobes. This central segment takes the form of 

 a papilla upon which the duct of the excretory organ opens. 

 They are accurately figured by Bouvier, who remarks that the 

 urinary papillje of the 4th and 5th legs are always independent 

 of the neighbouring parts of the proximal spinous pad, whereas 

 they are always adherent in Peripatoides suteri and sometimes in 

 P. orientalis ( P. leuckartii). We may now add that the condition 

 described above holds good in every detail for the southern 

 form too. 



