PLATE XI. 
Development of Ducarona, continued. Figures from N. Boprerzky, Waurer Faxon, Paut Mayer, 
Frirz Mttisr, Cart Ciaus, and Fern, Ricurers. 
1-9. Palemon. 
1. 
~ 
a. Anus. oc. Eye. 
ab. Abdomen. ocl. Ocellus. 
bl. Blastoderm. pd.  Proctodeum, or hind-gut. 
br. Gill. pl. Procephalic lobe. 
cp. Carapace. pp. Protoplasm. 
dp. Deutoplasm. py. Yolk pyramid. 
ep. Epiblast. re. Exopodite. 
gm. Gastruia mouth, ri. Endopodite. 
h. Heart. sd. Stomodxum, or fore-gut. 
hy Uypoblast. vm. Vitelline membrane. 
16. Labrum. a, Tail fold. 
ms. Mesoblast. 
n. Nerve. 
Epipodite. 
Antennal gland. 
Palpus. 
. Section of later stage of the cleavage. 
. Nauplius stage. 7, labrum. 
. Superficial ventral view of embryo at a later stage. 
. Longitudinal section of late stage in the development of the embryo. 
B 
mt. Metastoma. y- 
6 
€. 
ne. Nucleus. Epipodite. 
From Bobretzky, Ib JMBPIO.OTM YIEHMCTOHOPUXD. Sanne. Kiesckaro Oomecrsa 
Ecrecrsoucusirareseit, I1I., T. 1V., V., VI., 1873. [On the Embryology of Arthropods. Mem. Kieff 
Naturalists’ Soc., III., Pl. IV., V., VI, 1873.] 
Egg undergoing cleavage, superficial view. The cleavage is regular. Whether the first clefts reach the centre 
of the yolk or not Bobretzky was unable to determine, owing to the imperfection of his sections. At any 
rate the deutoplasm soon invades the core of the egg to such a degree that the subsequent clefts do not 
attain to the centre, and the segmentation becomes superficial. 
The cleavage products now have the form of long pyramids whose 
apices are fused in the deutoplasmic mass in the centre of the egg. The clear protoplasm, involving the 
nuclei, has collected at the bases of the pyramids. Later the boundaries of the pyramids become obliterated, 
while their protoplasmic bases become separated from the deeper food-yolk and form the cells of a superfi- 
cial blastoderm. 
. Gastrula stage, superficial view. 
. Gastrula stage, section. 
. Section showing the closure of the blastopore or gastrula mouth. 
dp, deutoplasm. 
m s, mesoblast, originating from the walls 
b1, epiblastic layer. hy, hypoblast. 
of the gastrula cavity. 
ab, abdomen. I, first antenna. II, second antenna. III, mandible. pJ, pro- 
cephalic lobe. 
. Longitudinal section through nauplius stage. The hypoblast cells have increased and passed into and absorbed 
the whole yolk, forming a solid mass of hypoblast in’ which the outlines of the cells are almost obliterated. 
pd, invagination of epiblast which forms the hind-gut. sd, invagination of epiblast which forms the fore- 
gut (esophagus and stomach). a, tail fold, between which and the proctodeum lies the rudimentary abdo- 
men. 76, labrum. 
The maxilla (IV, V) and maxillipeds (VI, VII, VIII) are 
oc, eye, formed in the procephalic lobes. 
A portion of the nuclei of the hypoblast 
cells have migrated to the periphery of the yolk, and the cells have assumed a pyramidal form, similar to 
the cleavage pyramids in Fig. 2. The protoplasm segregates in the bases of the pyramids, while their apices 
become lost in the central deutoplasmic mass, in which all trace of nuclei has disappeared. The wall of the 
mesenteron thus comes to form a single layer of pyramidal cells enclosing, and merging into, a central mass 
of food-yolk. The protoplasmic ends of the hypoblast pyramids finally separate as cellular layer, which 
forms the lining of the mid-gut and liver in the adult. Connection is formed first with the proctodeum, or 
hind-gut, and later with the stomodzum (cesophagus and stomach). The latter connection is not made until 
all the food-yolk in the mesenteron has been absorbed. x, ventral nerve cord ; 7’, supra-cesophageal nerve 
ganglion. . These originate from the epiblast; the latter from the procephalic lobes. , heart arising in the 
mesoblastic tissue. 
seen as bilobed buds. cp, fold which forms the carapace. 
