NOTES ON l’HK EMBRYOLOGY OE LIMULUS. 
573 
EXPLANATION OF PLATES XXXVII, XXXVIII, 
AND XXXIX, 
Illustrating Dr. J. S. Kingsley’s Paper on “ The Embryology 
of Limulus polyphemus.” 
Reference Letters. 
a. Anns. ab. Abdomen, ap. Appendage, b. Modified blastopore, be. 
Blood-corpuscle, bl. Blastoderm, bs. Blood-sinus, c. Coelom, cm. Com- 
missure. cn. Connective, co. Connective tissue, ct. Second larval cuticle. 
ex. Cephalothorax. dt. Deutovum. e. Eye. ec. Edge of carapax. ei. 
Epiblastic invagination for brain, eo. External opening of segmental organ 
ep. Epiblast. f. Flagellum of sixth pair of legs. fn. ? Funnel of segmental 
organ. ga. Gill-bearing appendage. gl. Gill-lamellae. gn. Ganglion. 
h. Heart, m. Mesoblast. mo. Mouth, mp. Mesoblastic partitions, mt. 
Metastoma. mu. Muscle. n. Nerve. nf. Nerve-fibres, ng. Neural 
groove, nr. Neural thickening, nu. Nucleus, o. Operculum, oc. Ocelli. 
p. Proctodaeum. pub. Abdominal appendage, pc. Procephalic lobes, pi. 
Pulmonary lamellae. pn. Pulmonary invagination. sg. Segmental organ. 
so. Somatopleur. sp. Splanchnopleur. st. Stomodaeum. stg. Stigma, t. 
Telson. x. Problematical organs of Fig. 3. y. Yolk. yg. Yolk-granules. 
The Roman numerals, I, n, in, &c., refer to the segments ; the Arabic, 1, 
2, 3, &c., to the appendages of the body. 
PLATE XXXVII. 
Fig. 1.—- Surface view of egg half an hour after attempted artificial im- 
pregnation. 
Fig. 2. — Same egg twenty-one hours later. 
Fig. 3. — Surface view of an egg twenty-nine hours after artificial impreg- 
nation, showing two peculiar protuberances on the surface. For detailed 
description of Figs. 1 — 3 see p. 544. 
Fig. 4. — Early embryo of Limulus. The lighter area ( m ) indicates the 
extension of the mesoblast ; the key-hole-shaped centre ( b ) is the modified 
blastopore. Osmic acid preparation. 
Fig. 5. — Embryo after the appearance of the compound eyes ( e ), tbe six 
pairs of cephalothoracic appendages (1 — 6), and the operculum (o). The 
blastopore has now divided into the pyriform mouth and anus. The neural 
groove (ng) is seen. Osmic acid preparation. 
