CATALOGUE OP TUNICATA. 61 



Colella, Herdm. 



The two species Colella pedunculaia and C. Thomsoni, obtained during 

 the "Challenger" Expedition, were fully described, and the present 

 genus was first formed for their reception by me in my Thesis on the 

 Synascidiaa, accepted by the University of Edinburgh for the degree of 

 Doctor of Science in March, 1880. This account of the genus Colella 

 was afterwards incorporated in the second part of my "Challenger" 

 Report, dealing with the Compound Ascidians, and published in 1885. 

 Briefly put, Colella includes pedunculated Distomidae, provided with an 

 incubatory pouch or diverticulum of the atrial cavity, in which the 

 embryos undergo their development. For a more detailed description I 

 must refer readers to the " Challenger " Report, Part II., p. 72. 



Nine species, and a variety, of Colella were obtained during the 

 "Challenger" Expedition. Four of these and the variety were from 

 Australian seas, and the present collection adds four newly described 

 species (one of which is possibly an old, imperfectly described, species 

 of Quoy and Gaimard), making in all eight species of Colella known from 

 the neighbourhood of Australia. 



The various known species of the genus may be distinguished as 

 follows : 



Peduncle branched ... ... ... ... 1 



Peduncle unbranched ... ... ... 2 



Lower end of peduncle branched ... ... 3 



Upper end of peduncle branched ... ... C. plicata. 



Peduncle short and wide ... ... ... C. cone re ta. 



Peduncle long and narrow... ... ... 4 



Tentacles all one size ... ... ... C.ramulosa. 



Tentacles of two sizes C. tenuicaidis. 



Peduncle longer than body ... ... 5 



Peduncle not longer than body ... ... 6 



Colour red C. pulchra. 



Colour blueish C. Thomsoni. 



Colour greyish-yellow ... ... ... 7 



Tentacles large ... ... ... ... C. pediinculata. 



Tentacles small C, Gaimardi. 



Colony wide at top ... ... ... ... 8 



Colony narrow at top ... ... ... 9 



g j Colour grey C. Murrayi. 



Colour with a reddish brown tinge ... do., var. rubidum. 



