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NIL — Report on the Tunicata collected during the Cruise of H. M.S. " Triton " in 

 the Summer of 1882. By W. A. Herdman, D.Sc, Professor of Natural 

 History in University College, Liverpool. (Plates XVI. to XX.) 



(Read 16th July 1883.) 



This collection was sent to me for examination some months ago by Mr 

 Murray. It may be conveniently divided into two very natural groups : — 



1. Asciuiacea, including the forms dredged or trawled from the bottom 



of the sea. 



2. Thaliacea, including the free-swimming pelagic forms captured by 



the tow-net at or below the surface. 



The small group of Ascidiacea contains no Compound Ascidians, and only 

 two* of the four families of Ascidia} Simplices known are represented in it. The 

 one of these families (the Cynthiidae) is represented by a single species only, while 

 the other (the Ascidiidse) contains the remaining three species, referred to the 

 two genera Ascidia and Ciona. One of those species of Simple Ascidians 

 (Ascidia tritonis) is new to science, the other three are well-known British 

 forms. 



This little collection of Ascidiacea is chiefly interesting (1) on account of 

 the depths at which the specimens were procured, and (2) on account of the 

 locality being one in which the Ascidian fauna had not been previously investi- 

 gated. Ascidia tritonis, though a new species, is not in any way aberrant or 

 strikingly peculiar, and hence, as far as the Simple Ascidians of the collection 

 go, the region explored by the " Triton " may readily be regarded as an exten- 

 sion of the British fauna. 



The second group — -the Thaliacea — is a very considerable collection, as may 

 be seen from the following list of the different localities. The most remarkable 

 circumstance in regard to it is that, with the exception of two specimens of 

 Salpa, the whole series is composed of one species, Doliolum denticulatum, of 

 which between five and six thousand specimens were collected. 



List of " Triton " Thaliacea. 



1882. 

 August 3rd— 4th. Surface. Doliolum denticulatum, about 100 specimens, 1 small one (2 mm. long). 

 „ 4th. Tow-net at a depth of 12 fathoms. Dol. denticulatum, 8 specimens, in absolute 



alcohol. 

 ,, 4th — 5th. Tow-net at a depth of 12 fathoms. Dol. denticulatum, about 1000 specimens; and 

 1 specimen of Saljpa runcinata (aggregate form). 



* See "Postscript," page 114. 

 VOL. XXXII. PART I. R 



