92 Prof. F. J. Bell on Pentastomum polyzonura. 



EXPLANATION OF PLATE IV. 



Fig. 1. Walckena'era Hasse.Uii. a, spider, magnified ; b, ditto, in profile, 

 withont legs or palpi ; c, slio^litly perspective view of caput ; d, 

 caput, from in front, showing tlie position of the eyes ; e, left 

 palpus, from in front and rather inside ; /, natural length of 

 spider. 



Fig. 2. Walckena'era nemoralio'ides. a, spider, magnified, S\ b, ditto, 

 in profile, with legs and palpi removed ; c, caput, from in fi-ont, 

 showing the eyes ; d, left palpus, from in front and rather on the 

 inner side ; e, radial joint of palpus ; g, 2 in profile, without 

 legs or palpi ; h, natural length of spider ; A:, genital aperture, $ . 



Fiff. 3. Walckena'era nemoralis, Bl. Part of palpus of c? . 



XI. — A second Note on Pentastomum poljzonum. 

 By F. Jeffeey Bell, M.A. 



In the sixth volume of the current series of the ' Annals ' 

 (pp. 173-176) I published a short note on the rediscovery of 

 t\\Q. Pentastomum poly zonum of Harley, two female specimens 

 of which had been acquired by the British Museum in 1880. 

 Lately we have received other specimens which formed part of 

 the collection of the late Dr. Edwards Crisp, but are without 

 any indication of origin* and not in first-rate condition. 



A short time since an interesting essay on the structure of 

 Pentastomum was published by Mr. W. E. Hoyle in the 

 ^Transactions of the Hoyal Society of Edinburgh' (vol. xxxii. 

 pp. 165-191), in which he describes a new species (P. ^;ra- 

 telis) , and gives an account of its anatomy. 



Mr. Hoyle was fortunate enough to have examples of both 

 sexes of the parasite, and he describes the male as being 

 13-17 millim. in length, and as having sixteen or seventeen 

 annuli. Of the two specimens which formed the basis of my 

 former note neither was male ; of the seven specimens now 

 received one is a male, and I have been able to observe that 

 it, while measuring 36 millim. in length, has only seventeen 

 rings, and that the most anterior of these are much less pro- 

 minent than they are in the female. In addition, therefore, to 

 the numerous points of similarity indicated by Mr. Hoyle, we 

 have another in the smaller number of annuli in the male 

 than in the female. Another point is to be observed in the 



* Although a careful search has been made in Dr. Crisp's collections, 

 there are no indications of the Pentastomum annulatum of Baird, which 

 did, I believe, on the dispersal of the Zoological Society's museum collec- 

 tions, pass into the hands of Dr. Crisp. It is greatly to be wished that 

 this type should be found. 



