430 D. J. SCOURFIELD ON TLYOCRYPTUS AGILIS. 



spicuons feature, but this is probably an inconstant character. The 

 setae fringing the ventral valve- margins are long and plumose ; those 

 arising from tlie hinder margins are plumose, but shorter than the 

 former, and furnished with an accessory spine or branch seated on 

 a small swelling (Fig. 3). This last character is by itself sufficient 

 to distinguish /. agilis from /. sordidus, for the posterior setae in 

 the latter give rise to from three to five or more accessory spines. 

 The first and second antennae are very nearly as in /. sordidus, but 

 perhaps rather more slender. The alimentary canal is, as usual in 

 this genus, a simple tube without caeca, but with a terminal con- 

 tractile dilatation in front of the rectum. The abdomen bears dor- 

 sally a single very large spur, which is hairy on its lower face. The 

 post-abdomen (Fig. 4) is large and broad, and armed with two 

 double rows of post-anal and a single median row of pre-anal teeth. 

 The outer row of each of the former comprises about nine long and 

 slender curved spines, and only just reaches to the anus, while the 

 inner row, consisting of about thiiteen short teeth, stretches just 

 beyond the anus. The pre-anal teeth are about eight in number, 

 the anterior being larger than tlie posterior members of the series. 

 In connection with these pre-anal teeth it must lie pointed out that 

 Kurz in his original figure shows the anterior two broad and leaf- 

 like (Fig 4 a), whereas in my specimens they were rather slender 

 and gradually tapering to the tip. In one case, however, I did see 

 a decided approach to the broad leaf-like form, and this, I think, 

 precludes the idea, which might naturally arise, that Kurz's speci- 

 mens and those found at the Botanic Gardens can be distinct 

 varieties. The terminal claws are long and slender, with two small 

 spines on the base of each. There are also three or four minute 

 setae on each side of the post-abdomen between the bases of the 

 claws and the large post-anal spines. The maximum length of 

 my specimens was ^^ in. 



The foregoing account relates to the female only, no males having 

 yet been recorded as far as I can ascertain. 



Concerning the habits of this form and its appearance when 

 living I have not much to say, as I only bad a few living specimens 

 under observation a very short time. My hope that some more 

 would be forthcoming this year has been disappointed, for none 

 have yet developed in the tank — at least, none were present so 

 recently as the 26th of last month. It might possibly be imagined 

 from the specific name that /. agilis is a very active creature, but 



