596 MALCOLM LAURIE. 



EXPLANATION OF PLATE XL, 



Illustrating Mr. Malcolm Laurie's paper on " Some Points in 

 the Development of Scorpio fulvipes/' 



Abbreviations. 



am. Amnion, ap. Appendix of diverticulum. A. S. Air-space. Bl. S. 

 Blood-sinus, c. Collar of diverticulum, co. Cord of cells on which embryo 

 feeds, ep. Epibiast. est. Epistome. hi. Heart, hy. Hypoblast, i. I. Inner 

 layer of ovarian tube. m. Muscles of stomodeeura. mes. Mesoblast. n, c. 

 Nerve-cord. o. Central eyes. o'. Lateral eyes. o. I. Outer layer of ovarian 

 tube. 0. d. Ovarian tube. o. n. Optic nerve, ov. Ovum. ;•. Nuclei of 

 retinal cells, s. Stalk of diverticulum, st. Stomodseum. stg. Stigma, v. 

 Vitreous layer, i/k. Yolk. The appendages are numbered i, ii, iii, &c. 

 Eor the sake of simplicity the diverticulum round the embryo has not been 

 figured, except in Fig. 14. 



EiG. 1. — Part of ovary of Scorpio fulvipes, to show the diverticula in 

 which the eggs are formed. X f . 



FiGr. 2. — Longitudinal section of a diverticulum and ovum at an early 

 stage. X -\°- . 



Fig. 3. — Transverse section of the lower part of a diverticulum, x ^-\^, 



YiG. 4. — Transverse section of the swollen " collar " of a diverticulum. 

 X J^. 



Fig. 5. — Transverse section of the solid coiled appendix in which the 

 diverticulum ends. X -^. 



Fig. 6. — Transverse section of a fully segmented egg. X ^f^. 



Fig. 7. — Transverse section of front end of a very young embryo, showing 

 stomodseum, amnion, &c. X ^^. 



Fig. 8. — Longitudinal section of an embryo slightly older than Fig. 7. 



Fig. 9. — Transverse section. Body of embryo considerably older than 

 Fig. 8. X ^^. 



Fig. 10. — Transverse section through head of same embryo, showing 

 stomodseum, chelicerae, &c. X ^f ^. 



Fig. 11. — View of the dorsal surface of an embryo, older than Fig. 9, 

 X * 



