SKI'^LKTO-TEOPHIO TISSUES AND COXAL GLANDS. 151 



The blood of Limulus contains a large quantity of Fredericq's 

 hseraocyanin, so that it may exhibit a deep indigo tint when in 

 quantity. The same is true of the Scorpion's blood. When 

 obtained in bulk — as I have obtained it from large specimens 

 of Androctonus funestrus — the blood exhibits as deep a 

 shade of indigo blue as does that of Limulus. 



The blood-corpuscles of Limulus and of two species of 

 Scorpion are drawn in PI. VIII, figs. 4, 5, 6. In measurement 

 they closely agree, being of unusually large size for Arthropods. 

 Usually, when shed, they exhibit an oval shape, and the more 

 elongated examples are as much as ywoo^^ i^^^^ lo^g- In both 

 Limulus and Scorpio the corpuscles are sometimes seen with 

 irregular amoeboid processes, and when observed in the living 

 state in the gill laminae of Limulus they very generally have an 

 irregular outline, and may be seen to undergo changes of 

 form. 



In both Limulus and Scorpio the blood-corpuscles are 

 remarkable for containing a number of coarse granules, 

 larger and more abundant in the latter than the former. 



The exact nature of these granules I have not determined. 

 They are highly refringent, and appear to be similar in sub- 

 stance with the granules observed in the protoplasm of the cells 

 of the lacunar tissue (see above, Section 3). 



9. The coxal glands of the Arachnida. 



In No. 221 of the ' Proc. Roy. Soc' (June 15th, 1882), I 

 described and figured the position of certain glandular bodies 

 — the " coxal glands," as I termed them — occurring in the 

 prosoma of Scorpio and its subgenera. The woodcut showing 

 the position of these glands is here reproduced. 



I showed that these bodies had been erroneously supposed 

 by Newport and others to be part of the alimentary canal ; at 

 the same time I identified with them the " brick-red glands " 

 discovered by Packard in Limulus. I now submit a woodcut 

 copy of Packard's figure of the brick -red gland of the right side 

 of Limulus polyphemus for comparison. It will be ob- 

 served that the position of the gland is closely analogous to 



