9-17. Development of Neparia Guorrroyi. igures from Extas Merscunikorr, WCTOPIA 
PASBIUTIA NEBALIA, 3ATMICORKb WMI. AKATEMIM HAYWb, XILL, CAHKTOUTEPBYPI'S, 
1868 [Development of Nebalia. Mem. Imper. Acad. Sci., XIII., St. Petersburg, 1868). 
9. Early stage showing partial segmentation (telolecithal). 48. 
10. Later stage. The blastoderm cells now form a cap over one pole of the egg. 42. 
11. So-called nauplius stage of the embryo. The rudiments of the two pairs of antenne and mandibles are present 
d, HW, 111). a@ 6, abdomen. 
12. Later stage in the development of the embryo. The seven anterior pairs of appendages are now present. 
Zé, labrum. a, anus. 
13. Still older phase. The dotted line from VIII passes a little forward of its proper place in the figure. 
14. Embryo at the time of leaving the egg. Most of the appendages are present. The body is still enveloped in 
a larval skin, c¢, and the abdomen is bent upwards. 4,8. 
15. Older larva after the larval skin has been cast off. 1V’, external branch of first maxilla. oc, eye. cp, cara- 
pace. 7%. 
16. Later stage. 7, rostrum. IV’, appendage of the first maxilla extending backwards over the branchial feet. 
VI-XIUII, branchial feet. Behind these are four pairs of abdominal swimming-feet. a 0°, eighth somite of 
abdomen bearing the two terminal styliform appendages (). 7% 
17. One of the phyllopod appendages. 1, inner branch. 2, middle branch. 3, outer branch. 24°, 
18—22. Development of Scuizopopa. SLigures from Evtas Merscunikorr and Caru CLats. 
18. Nauplius of Zuphausia, just hatched. A mouth opening is seen between the bases of the third pair of ap- 
pendages, but there is no anal orifice. From Metschnikoff, Ueber den Naupliuszustand von Huphausia. 
Zeitschr. wissensch. Zool., XXI., Taf. XXXIV., 1871. 
19. Later stage of the same. oc/, ocellus. 76, labrum. mt, metastoma or lower lip. IV, rudiment of first 
maxille. V, second maxille. VI, first maxilliped. The carapace is now present. The specimen figured 
was about to moult, and within the third pair of nauplius appendages are seen the mandibles of the next 
stage, when the function of these appendages becomes masticatory. From Metschnikoff, op. cit. 
20. Later stage (protozoéa) of a Luphausia larva from the Atlantic Ocean, seen from the ventral side. 14mm. 
long. The hind body (thorax and abdomen) has now acquired great length. The segmentation of the body 
is beginning in the region back of the first maxillipeds, i. e. in the thoracic region, the hinder or abdominal 
portion being yet uninvaded by segmentation. (f, frontal sense-organ, similar to that shown on previous 
plates in larve of Cirripedia, Apus, &e. Grobben (Arbeiten Zoolog. Inst. Wien., II. p. 262, Taf. XVII. 
figs. 74-76, 1879) has shown that the larva of Zuphausia also has a ‘‘dorsal organ” equivalent to that 
which we have seen in the embryos of many of the lower Crustacea. 7, intestine. a, anus. ¢ longitudinal 
muscles of the abdomen. From Claus, Untersuchungen zur Erforschung der Genealogischen Grundlage des 
Crustaceen-Systems, Taf. I., 1876. 
21, Still later stage (zoéa) of the same, lateral view. 23mm. long. The thoracic region behind the first maxil- 
liped (VI) is divided into its full number of seven somites, although they are extremely short. The abdo- 
men is also divided into six somites. The telson is not yet separated by a suture from the sixth segment. 
Underneath the cuticle of the anterior portion of the terminal segment are the rudiments of the posterior pair 
of abdominal appendages (not seen in the lateral view). The larva, unlike the typical zoéa, lacks the second 
pair of maxillipeds, and the antennz are still large swimming-organs. As the development proveeds, the tho- 
racic and abdominal appendages develop as two independent series from before backwards, the abdominal 
series being completed before the thoracic series. oc, eye. From Claus, Joc. cit. 
22. Second and third maxillipeds (VII,VIII) and the first and second ambulatory appendages (IX, X) of a Eu- 
phausia 44-5 mm. long. VII’, etc., outer branches of appendages. b7, gills. From Claus, loc. cit. 
