68 TUNICATA—APPENDICULARIANS CHAP, 
ducts merely breaking through to the exterior at the point 
marked g.d in Fig. 30. The spermatozoa are generally matured 
and shed before the ova, and thus self-fertilisation is prevented. 
The ova are very small, and little is known of the develop- 
ment, 
SS 
SS — 
Sn EA 
SS. a 
WSS ASS a SSE 
~ == 
~ - 
V\\/, 
Fic. 30.—Longitudinal optical section of Otkoplewra. Part of the tail is cut off. a, 
Anus ; at, atrial opening ; b7.s, branchial sac ; ¢.f, ciliated funnel ; ec, ectoderm ; 
end, endostyle ; ep.p, epipharyngeal ridge; g.d, opening of gonads to exterior ; 
ht, heart; hy.p, hypopharyngeal ridge; 7, intestine; m, mouth; mus, muscle- 
bands in tail; m, nerve-cord; ’, nerve in tail; 2.ch, urochord; x.g, nerve- 
ganglion ; ”.g’, ganglion in tail; oes, oesophagus ; o7.gl, oral gland ; of, otocyst ; 
ov, ovary; sg, stigmata; so, sense-organ ; sp, testis ; st, stomach ; 7, test. (After 
Herdman.) 
Classification.—There are two Families of Larvacea: First, 
the KOWALEVSKIIDAE, including only the remarkable genus 
Kowalevskia, Fol, in which the heart and endostyle are absent, 
and the branchial sac is provided with four rows of ciliated tooth- 
like processes. The two known species have been found in the 
Mediterranean and in the Atlantic. 
The second family APPENDICULARIIDAE comprises about eight 
genera, amongst which may be mentioned:—(1) Ovkopleura, 
Mertens, and (2) Appendicularia, Fol, in both of which the body 
is short (1 or 2 mm. in length) and compact (Fig. 30), and the 
tail relatively long, while the endostyle is straight. (3) Megalo- 
cercus, Chun, from deep water in the Mediterranean ; JL abyssorwm 
is the largest Appendicularian known, having a total length of 
