ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 887 



bearing a number of bairs like tbe metatarsus and tibia : c. g. Terri- 

 telari(B, Dysderidce. 



The remaining members of this class are further subdivided 

 according to the presence of one or two series of auditory hairs on 

 the tarsus. A single series is characteristic of AmanrohiidcB, 

 Agnlenidce, Philodromidce, ThomisidcB, aud Aitidce. Two series occur 

 in Drafisid(B, Anyphcenidce, and Lycosidce. 



Dahl has satisfied himself that these auditory organs can appre- 

 ciate not only sound, but also variations of atmospheric pressure, such 

 as winds. 



An olfactory organ is stated to exist on the maxillaD. On tlic sur- 

 face in front of which the mandibles work to and fro is a soft flat 

 tract, of a sieve-like appearance, beneath wliich occur a number of 

 long, polygonal processes, apparently fu.sed, but in reality separate, 

 which are in connection basally with a stout nerve-filarnent. Eather 

 by a process of exhaustion than from direct evidence as to their 

 function, Dahl afl&rms that this organ is olfactory in nature. It is 

 universally found in Arachnida, though in difierent stages of develop- 

 ment, being most fully developed in Pachyrjnatha, 



Anatomy of Pentastomum protelis.* — W. E. Hoyle gives a 

 detailed account of the anatomy of a new species of Pentastomum (P. 

 protelis) from the mesentery of Proteles cristatus. The most interest- 

 ing fact relates to the condition of the male sexual organs ; the vag 

 deferens passes down as far as the vesicula seminalis, and comes into 

 actual contact with it, though nx) communication between the two 

 existed ; this is in harmony with Leuckart's discovery that the gene- 

 rative organs of Pentastomum are formed of two distinct portions : 

 (1) a mass of cells segregated from the general tissue of the embryo, 

 and (2) an external invagination ; it is probable that in the species 

 described, tbe junction between these two portions takes place at the 

 point where the vas deferens comes into contact with the vesicula 

 seminalis, and it is not a little remarkable that this species should 

 present such a striking embryonic feature when the remainder of its 

 organization has attained such a comparatively advanced stage of 

 development. 



The paper concludes with some remarks on the subdivision of the 

 family Pentastomidaj ; and the author is of opinitjn that the two 

 genera Ltnrjuatula and Pentastomum ought to be separated, and gives 

 the following definitions : — 



Linrjuatula. Body flattened ; body-cavity sending out lateral pro- 

 cesses into the annuli ; hook gland diffuse ; opening of (X'sophagus 

 into tbe extremity of the intestine ; testis double ; vesicula seminalis 

 single. 



PentoJifomum. Body cylindrical ; body-cavity even, without lateral 

 prolongations ; a hook gland on either side of the intestine ; testis 

 unpaired; vesicula seminalis single (?) 



F. Jeflfrey Bell f suggests that this is the immature stage of P. 

 polyzonum which is found in large snakes. 



• Trana. Rov. Hoc. Edinb., xxxii. (for 1882-3) pp. lG.5-93 (2 pis.), 

 t Ann, an'l Mag. Nat. Hist., xiv. (1884) pp. 02-3. 



