CoTTRELL. — Styela coerulea (Quo// and Gaimard). 



171 



I'caches forwards very little i)ast the atrial siphon. The juuctiou between 

 the oesophagus and stomach is well marked, but tlie stomach tapers gradu- 

 ally into the mtesthie and rectum. There is no digestive gland. On the 

 surface of the stomach several large blood-vessels can be seen ; internally 

 the stomach has very prominent longitudinal folds. 



The gonads consist of two masses of short, thick, irregular, tube-like 

 structures, which are attached to the mantle, one mass on each side (fig. 4). 

 Sometimes these organs branch, and there are usually 6 to 9 or more of 

 them on each side. They are usually placed near the bend of the intes- 

 tinal loop, but may extend from the tentacles to the posterior end. The 



<XC <x 



Fig. 4. — Alimentary canal and gonads of Styela coerulea ; X nearly 2. The right side 

 of the body and the branchial sac have been removed, a, anus ; at, atrial 

 siphon; br, branchial siphon; g, gonads of left side; m, mantle; oe. oeso- 

 phagus ; r, rectum ; s, stoniach ; t. ring of tentacles. 



gonads and the alimentary canal are closely associated with numerous 

 pouch-like structures, which have been described under the name of 

 '• endocarps" and are common to several genera of the Cyntkiklae 



Habitat. — Rocky shores of Hauraki Gulf ; Great Barrier Island ; Ba}' of 

 Islands (Oliver). Common under rocks at low water. 



This species cannot be mistaken, as its beautiful colour makes it a very 

 conspicuous object. On the rocky shores of Hauraki Gulf it is the common 

 Ascidian ; it is also very common at Great Barrier Island. Mr. W. R. B. 

 Oliver informs me that this species is also very plentiful at the Bay of 

 Islands, where he collected some specimens, and I have to acknowledge my 

 indebtedness to him for placing these at my disposal. 



Apparently this Ascidian was collectecl in 1835 by Quoy and Gaimard, 

 of the ■' Astrolabe," who described and figured it under the name Ascidia 

 coerulea; but internal structure — viz., the 4 folds of the branchial sac on 

 each side, the condition of the alimentary canal, and the gonads — shows 

 it to belong to the genus Htyela. The figure illustrating their account of 

 the species exaggerates the 4-lobed structure of the branchial opening : 

 when partly closed both siphons are decidedly 4-lobed, but not to the 

 extent figured. Quoy and Gaimard also describe a double violet line in 

 the siphons, but none of my specimens shows this, nor does their figure 

 show it. 



I have collected several (jther sjx'cies in the gulf which do show violet 

 lines in the siphons, but exterjially they are quite difterent, and have no 



