114 ON THE LARVA OF AN ASCIDIAN FOUND AT THE LAND'S END. 



earnest investigation by many of the best observers on record will, 

 I hope, be sufficient excuse for my calling your attention to the 

 subject to-night. 



EXPLANATION OF THE DIAGRAM. 



Rough diagrammatic representation of the larva of Lejrtoclinum. 



Figures 1 and 2 are drawn from actual preparations, but figures 2 to 4 

 inclusive are more or less adapted from, or suggested by, Reichart's 

 figures of the larva of Botryllus violaceous. 



Pig 1. — Egg containing a fully developed larva ready to escape. 



Fig 2. — Larva. The fin-like membranous expansions of the test of the 



tail, being directed towards the eye or downward, are not 



seen. 

 Fig 3. — Transverse section of the tail. 



Fig 4. — Longitudinal section of a portion of the tail cut in a plane at 



right-angles to the fin-like expansions. 



A.— Body. 



B.— Tail. 



a. External tunic and vitelline membrane of the egg. 



b. External structureless test of the body. 

 b'. „ „ ,, of the tail. 



C.C.C. Anterior cupuliform suckers. 



d. Circlet of cellular outgrowths. 



e. Eye-spot. 



/. Opening of the branchial chamber. 



g. Cells of the body -wall. 



h. Large nucleated cells of the contractile and muscular portion of 

 the tail, forming a sheath round the central axis. 



i. Central axis of the tail. (Supposed chorda dorsalis). 



h. Terminal fin-like portion of the test of the tail showing the ray- 

 like striae. 



I. Upper fin-like longitudinal expansion of the test of the tail. 



m. Lower ditto. 



n. Gelatinous substance of the fin-like expansion. 



