PALAU Bh Ve 
aen, Anterior hypoblast cell. pnd. Male pronucleus. 
an. Anus. pn. Female pronucleus. 
cen. Central hypoblast cell. t. Testis. 
cr. Cirrhi. od. Vas deferens.~ 
ec. Epiblast. vm. Vitelline membrane. 
gen. Beginning of the genital system. a. Frontal papilla. 
ve Intestine. B. Spiral canal. 
lb. Labrum. ys Gland. 
len. Lateral cells, containing hypoblastic elements. €. Gland. 
Ms. Cells containing the elements of the mesoblast. ¢. Tactile organ. 
mt. Metastoma or paragnathite. UB Cement gland. 
n. Nervous system. o- Receptaculum seminis. 
n'. Secondary supra-cesophageal nerve-ganglion. Al, Tergum. 
nc. Nucleus. 2, Scutum. 
oc. Eye. a3, Carina. 
ocl, Simple eye. M4. Carino-lateral compartment, 
oes. esophagus. 9, Lateral compartment. 
ovd. Oviduct. a6, Rostrum. 
pe. Polar cell. {3 Tail. 
pms. Primitive mesoblast cell. 
The Roman numerals denote the appendages in their consecutive order. See explanation of Fig. 28, infra. 
1-5. Development of Crrripevia, continued. Figures from ALEXANDER AGassIzZ and 
CrLavs. 
1-4. Stages in the development of a Balanus from Newport, R. I., reared in confinement directly from the 
Cart 
larvee 
represented on PI. III. figs. 23, 24, and showing the metamorphosis of the free-swimming larva into the 
sessile adult. From drawings by A. Agassiz, August 29, 1872. 
1. The bivalve shell of the Cypris stage is becoming split up through calcification into the compartments and 
cy, cirrhi, representing the swimming-feet of the Cypris stage 
2. Later stage, seen from above. The cirrhi are retracted within the shell. 
3. Still older stage, side view. A, tergum. A2, scutum. 
4. Seen from above, cirrhi retracted within the operculum. 
opercular valves are seen the marginal compartments. 
lateral compartment. a°, rostrum. 
5. Pupa stage of Lepas fasciculata. ocl, median eye. oc, paired eye. 
From Claus, Die Cypris-iihnliche Larve (Puppe) der Cirripedien. 
Naturwissensch. Marburg, IX., Suppl. 5, Taf. I. fig. 2, 1869. 
opercular valves of the adult. 
Al, tergum. A?, seutum. Surrounding 
a3, carina. A}, carino-lateral compartment. 
&, abdomen. I, prehensile anti 
Schriften Gesellsch. Beford. gesa 
6-28. Development of Coprropa. Figures from Cart CLaus, ALEXANDER V. NORDMANN, 
CaRL GROBBEN. 
6-13. Achtheres percarum. 
Zeitschr. wissensch. Zool., XI., Taf. XXIII., XXIV., 1861. 
6. Larva at the time it leaves the egg. Only the two anterior pairs of appendages of the typical nauplit 
TUM. 
these 
a 
enne, 
mmt, 
and 
6-11, 13, from Claus, Ueber den Bau und die Entwicklung von Achtheres perca- 
as are 
present (I, II), and both of them are simple and unsegmented. Beneath the cuticle may be seen the six 
following pairs of appendages : 
ming-feet (VII, VIII), which become functional after the next moult. 
mandibles (JIT), maxilla (LV), maxillipeds (V, VI), and two pairs of swim- 
a, frontal papilla, in which is the 
opening of the coiled canal, 8. This is filled with a viscid secretion probably brought into play when the 
larva attaches itself to its host. 
7. Mouth-parts under the cuticle of the same stage, seen from the side. 
The letters 7b are in the place of the 
labrum. Directly below is seen one of the pair of protuberances which lie on each side of the labrum, fol- 
lowed by the mandibles (IIT), maxille (IV), and two pairs of maxillipeds (V, VI). 
8. Hinder part of the body of same stage, the cuticle having been removed so as to expose the swimming-feet 
and the caudal fork. 
