PART IV—ON OIKOPLEURA TORTUGENSIS, A NEW APPEN- 
DICULARIAN FROM THE TORTUGAS, FLORIDA, WITH 
NOTES ‘ON ITS EMBRYOLOGY. 
By Witit1AM KeEritH Brooks AND CARL KELLNER. 
(Plates 3-8.) 
INTRODUCTORY. 
A large appendicularian (plate 3, fig. 4) in its house is found in abundance 
in the vicinity of the Marine Biological Laboratory of the Carnegie Institu- 
tion of Washington at Tortugas, Florida. It is, no doubt, widely distributed 
along the coast of Florida, as it has been found by Dr. Mayer and Pro- 
fessor Brooks at Miami, and by Mr. Kellner in the Tortugas. The speci- 
mens are from 5 to 8 mm. long, and occur in great swarms at the depth 
of from 5 to 8 fathoms. They belong to the genus Ozkopleura and to a 
species that seems to be new, although its differences from O. longicauda 
and O. intermedia of Lohmann are slight. The house (plate 3, figs. 4 and 
5) is large, about 20 mm. in diameter, and nearly spherical. In its internal 
structure it resembles the houses that have been described in other species 
of the genus. 
Most of the houses contain small appendicularias of various sizes, 
but all are well advanced and in the appendicularia-stage. It is possible 
that these are the young of the animal in whose house they are found, 
but it is also possible that they have been drawn into the house by the 
current of water and that they are not, of necessity, the young of the 
species which forms the house. 
On the tails of some of the specimens (plate 7, fig. 13) are the eggs and 
early stages in the development of an appendicularian which may be Ovko- 
pleura, although it is possible that they belong to some other species. The 
eggs (plate 7, fig. 16) are inclosed in thick capsules of follicle-cells. Some 
are loosely attached to the tails, while others (plate 7, fig. 19) have, at one 
end, a process of modified follicle-cells that penetrates the tail like a root 
and firmly attaches the egg. Two embryos, at two successive stages of 
early development (plate 7, figs. 20 and 15) were found. They are deeply 
rooted in the tail by a process that penetrates the blood-sinus of the 
adult, and the embryos are parasites. On the ventral surface of the older 
embryo (plate 7, fig. 14) the two spiracles, opening to the exterior at 
one end and into the respiratory pouches of the pharynx at the other, 
prove that the embryos are appendicularians, although we have not been 
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