in the Spiders of the Genus Lycosa. 1 7 



individuals already hatched, but still contained in this sac, were 

 employed by me in my researches. It will not, perhaps, be use- 

 less to those who may wish to repeat my observations, to remark 

 that the young Lycosa, like most of the other Spiders, undergo 

 a moult in the interior of the ovigerous sac. The individuals 

 which have already undergone this moult, or in which it is ap- 

 proaching, are unfit for observation. The former bristle with 

 opake hairs ; and the latter already present, beneath the integu- 

 ment which they are about to throw off, the hairs characteristic 

 of the following phase. It is therefore immediately after hatch- 

 ing, and before the preparations for the moult, that the Lycosce 

 must be studied, if we wish distinctly to recognize their circula- 

 tory apparatus. Even at this period, the young individuals 

 possess a great resemblance to the adult. All the organs are 

 formed, with the exception of the abdominal portion of the 

 digestive tube, with its appendages, and the reproductive organs. 

 The intestine and the glands which are dependent on it (liver, 

 urinary glands) are represented by a strongly refractive mass 

 of a brownish-yellow colour — the unassimilated residue of the 

 vitelline emulsion which formerly filled the membrane of the 

 egg. In the cephalothorax we also find a residue of the vitellus 

 enclosed in an annular stomach and its csecal diverticula. 



The heart, or dorsal vessel, is situated on the median line, 

 exactly following the curve of the dorsal surface. Seen in pro- 

 file, it seems to describe nearly a semicircle. It presents its 

 maximum breadth in the immediate vicinity of the abdominal 

 peduncle, and from this point it gradually diminishes in calibre 

 to its posterior extremity. Its transverse section is not circular, 

 but elliptical, or, rather, reniform, the greater convexity of this 

 section being turned upwards. At different parts the heart 

 presents lateral dilatations, or, rather, diverticula, arranged in 

 pairs. These diverticula are of the form of wide cones, of which 

 the base is continued into the wall of the heart. There are 

 three pairs of them, and the last are much less developed than 

 the preceding ones. Sometimes I have fancied that I could see 

 a fourth, still further back ; but with regard to this I have not 

 been able to arrive at certainty. At the level of each pair of di- 

 verticula there is a pair of those orifices like button-holes which 

 were first discovered by Strauss in Insects, and which so many 

 anatomists have since detected in the most diverse forms of 

 Arthropoda. I shall retain for them the name of venous orifices, 

 rather than that of atrioventricular apertures, which has often 

 been given to them. These apertures are not exactly transverse, 

 but oblique, their dorsal or inner angle being directed a little 

 forwards, and their outer angle a little backwards. This latter 

 advances slightly beyond the limits of the heart properly so 



Ann. % Mag. N. Hist. Ser. 3. Vol. xv. 2 



