PLATE III. 



Development of Cirripedia. Figures from Fritz Muller, W. Lilljeborg, Charles Darwin, 

 P. P. C. HoEK, Carl Glaus, Alexander Agassiz, and C. Spence Bate. 



1-7. Development o( Rhizoccphala. 



1-6, from iliiller, Die Rhizoceplialen, eiiie neue Gruppe schmarotzender Kruster. Arch. Naturgesch., XXVIII. 



Taf. I., 1862 ; Die zweite Entwickelungstufe der Wurzelkrelise (llhizoccphala^ . Ibid., XXIX., Taf. III., 



fig. 1, 1863. 



1. Egg from the brood-chamber of Lcrnwodiscu.9 PorceUancc, with four cleavage spheres. Magnified 90 diameters. 



2. First larval stage, or nauplius, of the same, from below, magnified 180 diameters, cji, margin of carapace. 



lb, labrum. ocl, ocellus, vt, remains of the yolk. I, II, III, first, second, and third pairs of swimming- 

 feet. There is no mouth at this stage. A pair of frontal sensory threads is piesent, although not repre- 

 sented in the figure. 



3. Second or pupa stage in the development of the same. The dark oval body is the nauplius eye, now of 



extraordinary dimensions. Paired eyes are not present. The carapace has become folded together so as to 

 enclose the body. The second and third pairs of appendages of the nauplius have been discarded, the first 

 pair have become prehensile, adapted for the attachment of the larva, and si.x pairs of swimming-feet 

 (VI-XI) are present on the tliorax. |, posterior or abdominal part of the body, ending in a pair of two- 

 jointed processes, each bearing two terminal setie. The pupa attaches itself by the prehensile antennje to 

 the abdomen of its host, throwing out rootlike filaments which entw ine about its intestine or ramify through 

 its liver, drawing nourishment therefrom. The remaining appendages are cast off. 



4. Adult, attached to the ventral side of the abdomen of a Porcellana. Slightly magnified. 



5. A smaller specimen removed from its host, viewed from the ventral side, magnified 15 diameters, ov, ovary, 



t, testis, o, orifice of the brood-chamber. /3, chitinous shield, y, crown. 



6. The portion of the adult Lernmodlscus which lies within the Porcellana, magnified 25 diameters, i, intestine 



of the Porcellana. y, crown. 5, chitinous plate, e, rootlike processes growing about the intestine of the 

 Poixcllana. 



7. Exuvios of Peltogaster sulcatus, pupa stage, fi.xed by the prehensile antennae (1) in the opening of the mantle 



of the adult, magnified 200 times. 0, anterior end of adult Pclloijaslcr. From Lilljeborg, Supplement au 

 Memoire sur les Genres Liriopc et Pcltorjnster H. Rathke. Nova Acta Reg. Soc. Scient. Upsal. [3.] III., 

 PI. VIII. fig. 31, 1860. 

 8-12. Development of Cnjptophialus minutus, from Darwin, A Monograph on the Subclass Cirripedia. Bnlanidm, 

 PI. XXIV., London, 1854. 



8. Oval embryo. 35 times the natural size. 



9. Later stage. Two horns (I) are developed at the anterior part of the body, and one, representing the abdo- 



men (a b), at the posteiior end. On same scale as the last figure. 

 10. Later stage. The posterior horn has .shrunk. The two anterior horns have approached each other on the 

 future ventral surface and contain witliin them the prehensile antennae of the later stage. At this stage the 

 larvse adhere by the tips of the anterior horns to the inner tunic of the sac of the parent. On same scale 

 as the last figure. 



