PLATE XIV. 
Development of Ducarona, continued. Figures from Wautmr Faxon and Cart Craus. 
a. Anus. sp. Spinous process of second antenna of zoéa. 
ab. Abdomen. st. Stomach. 
br. Gill. a, Dorsal spine. 
h. Heart. 8B. Ophthalmie artery. 
t. Intestine. y. Spine on the second somite of abdomen. 
16. Labrum. 8. Lateral spine of carapace. 
oc. Eye. e. Mandibular palpus. 
tr. Rostrum. ¢. Tendon of mandibular muscle. 
re. Exopodite. y-  Retinaculum. 
ri. Endopodite. 
1-4. Carcinus menas (continued from Pl. XIII). From Faxon, op. cit., Pl. II. 
1. First zoéa stage, immediately succeeding the stage figured on the preceding plate. VIII, IX, X, rudimentary 
third maxillipeds and first and second ambulatory appendages. The abdomen has six segments, the telson 
being not yet separated from the sixth somite. 
2. Tail of the same stage. The Arabic numerals indicate the homology of the spines with those of the tail of 
the protozoéa (Pl. XIII. fig. 17). 
3. First antenna of the same stage. 
4. Second antenna of the same stage. s p, spinous process corresponding to the spine on the second antenna of 
larvee of prawns (PI. XI. fig. 11, &c.) and Pagwride (Pl. XII. fig. 22). 7 e, squamiform process, homologous 
to the external branch of the antenna of larval Macrowra, to tle antennal scale of adult Macrowra. Both of 
these parts become aborted in the adult. The flagellum (endopodite) of the second antenna of the adult is 
wanting in the youngest zoéa stages, or represented only by a small tubercle at the base of the squami- 
form process. 
5-11. From Claus, Untersuchungen zur Erforschung der Genealogischen Grundlage des Crustaceen-Systems, 
Taf. X., XI., Wien, 1876. 
5. Later zoéa stage of a Portunid from Chili. 4mm. long. This is probably the last zoéa stage, preceding the 
megalopa. The first and second maxillipeds still serve as swimming organs. The five ambulatory legs 
(IX- XIII) are quite largely developed but still functionless. From the time of their first appearance 
they are simple appendages destitute of external swimming branches. The chela is already prominent on 
the first pair (IX). The second to the sixth abdominal somites are now provided with appendages. The 
last pair (XIX) do not anticipate the others, as in Pugwrus (Pl. XII.) and most Macroura (e. g. Pencus, 
Plo UX., Lucifer, Pl. X.). 
6. First antenna of the same. ve, outer branch. The inner flagellum, wanting in the earlier zoéa stages, is 
developing as a sac-like process. 
7. Second antenna of the same. The flagellum (72, wanting in fig. 4) is now quite well developed and seg- 
mented. 
8. Mandible of a younger zoéa stage of a Brachyuran (Fissocaris) showing the commencement of the growth of 
the mandibular palp (€) which is wanting in the earliest zoéa stage. 
9. Mandible of the late zoéa stage of the Portunid represented in figs. 5-7. , palpus. 
10. First maxilla of young zoéa stage of Thia polita. 1, 2, basal joints (protopodite of Huxley). 77, endopodite 
in the form of a two-jointed palpus. 
11. Second maxilla of the same. 1, 2, basal joints or protopodite, each joint presenting a bilobed blade. 77, 
endopodite, also bilobed. 7 e, exopodite or scaphognathite. 
12-26. Cancer from Newport, R. I. From drawings by Faxon, July, 1879. 
12. Megalopa stage. Among the Brachywra no schizopod stage is found, but the zoéa passes into the megalopa 
phase, in which most of the characters of the adult are seen. The abdomen, however, is largely developed, 
and provided with swimming-feet. The megalopa stage of the Brachyuran corresponds very closely with 
the adult Anomouran. The maxillipeds are now converted into mouth parts, and the five Decapodal legs 
have their full development. The candal fork of the zoéa has become a telson plate similar to that of the 
adult. The crossed lines on the left of the figure indicate the natural size. 
13. First antenna of the same. 
