42 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



a few sections the endostyle becomes again shut off from 

 the pharynx, so that the opening between the two is very 

 small and the greater part of the endostyle is not a canal 

 as in most Tmricata, but a closed in tube (compare PL 

 IV. fig. 9, en.). Its close resemblance both in transverse 

 (PL IV. fig 3) and in longitudinal (fig. 9) section to its 

 homologue the thyroid involution in the larval lamprey is 

 more marked in this form, I think, than in any Tunicate 

 yet figured. This endostyle differs considerably from that 

 of Vexillaria speciosa as figured by Eisen. 



Twenty sections further forward (PL IV. fig 4) we find 

 the body greatly reduced in size, as we are now not far 

 from the anterior end ; while the tail is still very large. 

 The branchial sac or pharynx is small and is transversely 

 elongated. Above it we find the nervous system now 

 becoming of considerable size, and ventrally is the closed 

 endostyle composed of large glandular cells arranged below 

 a small circular lumen. Six sections further forward (PL 

 IV. fig. 5) we find the body and the branchial sac still 

 smaller, the endostyle large but with no lumen now, and 

 the nervous system larger than before with the otocyst 

 attached to it, on the left side. On each side of the bran- 

 chial sac is seen a large glandular mass w^hich is the 

 posterior end of an elongated cylindrical or sausage shaped 

 closed gland lying at the side of the mouth (PL IV. fig. 5). 



This section shows also the very large ciliated infundi- 

 bulum (fig. 5, d.t.) which opens into the dorsal edge of the 

 branchial sac, on the right side, and which probably corres- 

 ponds to the opening of the hypophysial duct on the dorsal 

 tubercle of an Ascidian. A few sections further forward, 

 in No. 257, we see this organ still better, and the middle 

 portion of this section is shown more highly magnified 

 (X600) in PL IV. fig. 6. The pharynx is thin walled and 

 irregular in shape with the ciliated funnel opening into the 



