83 
of Edinburgh, Session 1880-81. 
The most remarkable peculiarity of this genus is the structure of 
the branchial sac. It is merely a skeleton compared with that 
organ in other Simple Ascidians. The system of fine longitudinal 
or inter-stigmatic vessels is entirely wanting, so that the large 
meshes are not broken up into true stigmata. It seems probable 
from Macleay’s description * that the branchial sac of Cystingia 
griffbthsii has a similar simple structure. 
Culeolus murrayi , n. sp. 
External appearance . — Shape of the body irregularly pyriform, 
anterior end attenuated, ending in the stalk; posterior end blunt and 
broad, dorsal and ventral edges nearly straight and parallel in their 
posterior two-thirds, tapering suddenly in the anterior third. Stalk 
of moderate length, turned towards the branchial aperture. Bran- 
chial aperture placed rather on the dorsal side of the anterior end, 
being under the stalk, which is terminal. Atrial aperture in the 
middle of the posterior end, and directed posteriorly. Surface very 
irregular, thrown into deep creases ; a belt of close-set minute 
projections surrounds the atrial opening, cutting off the posterior 
third by a very irregular line. The rest of the surface is finely 
granulated, the granulations being larger in the neighbourhood of 
the apertures. Length of body, 6 cm. ; breadth, 4 cm. ; length of 
stalk, 15 cm. 
Test moderately thick, tough but soft and flexible; quite 
opaque. 
Mantle adhering to the test, but easily separated, thin ; muscle 
bands strong, but distant. 
Branchial sac large and delicate, having six folds on each side, 
those at the dorsal edge closer and more distinct than those at the 
ventral, the pair next the endostyle being very slight. Transverse 
vessels alternately larger and smaller. Internal longitudinal bars 
wide, four between each pair of folds. Meshes vertically elongated, 
large. Spicules in the vessels large and branched. 
Endostyle conspicuous, white, and very irregular in its course ; 
richly supplied with large and much branched spicules, having a 
definite arrangement. 
* Trans. Linn. Soc., vol. xiv. 1823. 
