DE. T. 8. COBBOLD ON STBON&TLUS AENFIELDl. 285 



the date above mentioned many other examples were from time 

 to time submitted to my notice, — another pupil, Mr. Hassall, 

 procuring and mounting these worms with much success. 



Steonq-tlfs Aenpieldi {Gohi.y. 



Mouth simple ; oesophagus short, slightly constricted ; body 

 with very fine strise ; vulva of the female a little above the anus ; 

 tail of male with trilobate hood, rather broader than long ; rays 

 complete, posterior ray broad and united to its fellow at the base, 

 bifurcate at the end ; mid ray narrow, cleft to the centre ; 

 postero-lateral ray long, variable in width ; spicules equal, with 

 an accessory piece ; tail of female short, sharply pointed. Yivi- 

 parous. Males 1| inch long; females 3 to 3g inches. 



Sab. Trachea and bronchi of the ass (Uquus asinus). 



The anatomical points that call for special notice are such as 

 refer to the morphology of the hood and its rays, to the position 

 of the vulva, and to the structure of the embryo. The ray- 

 pattern contrasts strongly with that of 8. micrurus. I have 

 recently verified Schneider's description of the rays of /S. micrurus, 

 ray for ray. Unpublished figures in my possession show only a 

 relatively greater length of certain rays than Schneider's original 

 plan suggests. This applies more particularly to the anterior 

 ray. In my specimens of 8. micrurus the innermost division or 

 cusp of the trifid end of the posterior ray is also more strikingly 

 pronounced. Contrasting the hoods of 8. micrurus aud 8. Arn- 

 Jieldi, the disconnected character of entire series of rays at their 

 bases is of itself sufficiently distinctive of the former species ; 

 whilst, as regards the individual rays, I need only further refer to 

 the paramount aspect of the posterior ray and its bifid extremity 

 in 8. Arnfieldi. Equally diagnostic of 8. Arnjieldi is the position 

 of the reproductive outlet in the female, which is placed above 

 the anus at a distance of only 1 millim. from the end of the tail. 

 In 8. micrurus the distance is 18 millim. (Schneider). The eggs 

 occur in prodigious numbers, probably in excess of what is seen 

 in 8trongylus filaria of the sheep, in which species, according to 

 Mr. Beulah, each female carries 300,000 embryo-containing ova. 

 My original estimate for 8. micrurus was one third of this 

 number. The viviparous character of 8. Arnfieldi is readily 

 tested by pressure under a cover-glass, when embryos will escape 

 from the vulva. An embryo thus freed already shows a well pro- 



LINN. JOTJEN. — ZOOLOGY, TOL. XIX. 23 



