2 



DR. E. H. VINEN ON A. CURIOUS FORM 



double, placed near the lateral margins and below the anterior 

 third of the segment. Caudal segment furnished with twelve 

 spines or setae, eight long and four short ; the former being retro- 

 verted and disposed in pairs, alternating with the latter, which are 

 somewhat nearer the extremity. 



In addition to these characters, I may remark that the head 

 appears to be supplied with a complicated buccal apparatus, but 

 the preservative medium has rendered the parts so transparent 

 that I refrain from hazarding a precise description of its several 

 parts. Moreover, in different examples these appearances are dis- 

 similar, whilst the cephalic segment itself is proportionally longer 

 in some cases than in others. The eye-spots are always distinct, 

 more or less elongated, each evidently consisting of two separate 

 pigment-masses, the line of demarcation being clearly defined. 

 In the specimen figured a on the slide, the eyes are much more 

 elongated and more uniform in outline ; being, nevertheless, thicker 

 behind than in front. Connected with the eyes and buccal appa- 

 ratus there are two laterally disposed muscular masses, which 

 almost fill up the longitudinal halves of the cephalic segment. 

 The buccal cavity itself is tolerably well defined, being funnel- 

 shaped and apparently closed behind. The oesophagus takes its 

 origin at the upper and back part of the sac, immediately behind 

 a peculiar form of dental apparatus which guards the pharyngeal 

 opening. This structure forcibly reminds one of the gastric teeth 

 found in decapodous Crustaceans, and appears to consist of a 

 central and two lateral horny pieces, which, acting upon one 

 another, serve to comminute the food only partially broken up 

 by the buccal organs. The intestinal canal can be traced through- 

 out the entire series of segments, and on either side of it runs a 

 conspicuous vessel filled with highly coloured blood. I have not 

 observed any trace of reproductive organs, a circumstance which 

 alone renders it highly probable that we have to do with a larval 

 insect. The last or thirteenth segment is considerably narrower 

 than those of the body proper. The eight long spines are jointed 

 at the base, where they are comparatively thick, becoming gradu- 

 ally attenuated towards the tip ; the segment itself is also slightly 

 increased in breadth at the lower end. The length of each spine 

 is somewhat less than that of the caudal segment, and fully four 

 times longer than those of the smaller series placed nearer to the 

 end of the segment ; these latter project at a right angle from the 

 tip, and do not appear capable of retroversion. 



