60 THE VOYAGE OF H.M.S. CHALLENGER. 



tail-less. 1 This most interesting developmental difference does not seem to be accom- 

 panied by any structural peculiarities in the adult form, which apparently does not 

 differ generically from Molgula. 



Glandula, as I pointed out in the Preliminary Eeport, 2 does not belong to the 

 Molgulidae, but should be placed in the sub-family Styelinse of the Cynthiidse. 



Gymnocystis was founded by Giard in 1872 3 for van Beneden's Ascidia ampulloides, 

 which has been so often described, and referred to so many different genera. This species 

 is undoubtedly one of the Molgulidse, but I see no reason for separating it from Molgula. 

 Giard distinguishes it chiefly on account of the test, which is smooth and semi-cartila- 

 ginous, like that of some species of Ascidia. This kind of test is, however, found 

 in several undoubted species of Molgula (e.g., Molgula gregaria, Lesson), and graduates 

 into the condition characteristic of the genus. I agree, therefore, with Lacaze-Duthiers 

 in referring van Beneden's Ascidia a/m/pvlloides to the genus Molgula. 



Pera, Stimpson, is probably either a Molgula, or an Eugyra. Nothing in the 

 description warrants our considering it as the type of a new genus. The species 

 described by Macdonald, 4 from the Bellona reefs, under the name of Pera huxleyi seems 

 to be a Rhodosoma, and in that case belongs to the Ascidiidse. 



Lithonephrya is characterised by Giard 5 as having the renal organ occupied by a 

 large brown concretion. Otherwise it seems identical with Molgula. 



Under the names of Ccesira parasitica, Ccesira Jicus, and Ccesira pellucida, Macdonald ° 

 described in 1859 three species of Simple Ascidians from Australia. They are evidently 

 Molgulidae, but whether or not they differ generically from Molgula and Eugyra is very 

 doubtful. The tribe Cynthise Caesirse of Savigny includes the single species Cynthia dionc, 

 which seems from the figures and description, 7 notwithstanding the assertion that both 

 apertures are four-lobed, to belong to the Molgulidae, and probably to the genus Molgula. 

 Heller 8 states that its nearest ally is Stimpson's Glandula. I cannot endorse this, as 

 the latter genus is closely allied to Styela, while I consider Savigny 's Cynthia dione a 

 species of Molgula. 



Ascopcra was founded 9 for the reception of two very large new species from the 

 Antarctic. They are attached, pedunculated, and not incrusted ; the chief peculiarity, 

 however, is in the branchial sac, as the stigmata are never arranged in spirals, no 

 infundibula being present. 



1 See Lacaze-Duthiers, Ase. Simp, des cotes de France. 



2 Proc. Roy. Soc. Edin., 1880-81, p. 231 



3 Archives de Zoologie experimentale et generale, t. i. p. 405. 



4 J. D. Macdonald, Jour. Proc. Linn. Soc, 1862. 



6 Arch, de Zool. exper., t. i. p. 404. 



J. D. Macdonald, Trans. Linn. Soc, vol. xxii. p. 367. 



7 Mem. sur les Anim. sans Vert., p. 153, pi. vii. tig. 1. 



8 Unlemu'h. u. d. Tun. d. adriat. u. Mittelmeer. , Abth. iii. p. 2. 

 3 Preliminary Report, Proc. Roy. Soc. Edin., 1880-81, p. 238. 



