508 MR. JAMES RITCHIE ON HYDROIDS [May 28, 



This operculum is frequently drawn within the hydrotheca. The 

 aperture faces obliquely vipwards, 



The gonosome is absent. 



Locality. Creeping upon a leaf found in one of the bottles 

 containing Mr. Orossland's collection of tunicates from Mattiota, 

 St. Vincent Harbour, Cape Yerde Islands. 



The peculiarly shaped hydrothecse in the present specimen bear 

 some resemblance to those of Sertularia lucernaria Kirchen. 

 1864; but in that species the aperture is almost horizontal, with 

 a very distinct margin, the hydrothecse are widely separated, 

 and the colonies are branched, with a bushy habit of growth, 

 altogether different from the minute, simple, and scattered 

 colonies of S. Icevimargi7iata. 



Family Plumulariid^. 



PiiUMULARiA HALECioiDES Alder 1859. 



This species is represented by a few specimens, attaining a 

 maximum height of 2'5 cm., which agree closely with the de- 

 scription of Hincks (1868). The following variations from and 

 additions to that description were noted : — The branches, which 

 are rare and may arise on any side, spring in the specimens 

 examined, not from the original hydroclade-bearing tube, but 

 from one of the secondary tubes of the stem-fascicle ; the hydro- 

 clades bear up to six hydrothecse in place of Hincks's maximum 

 of four ; intermediate athecate internodes are not always present 

 between thecate internodes, thus in 100 internodes examined 

 only 31 were athecate and intermediate, a pair of the latter 

 rarely occurring together ; the gonangia, for the most pai-t 

 strongly ringed, occvir not only on the stem but also on the hydro- 

 rhizal tubes. Similar variations have been noted by Billard 

 (1904, pp. 181 et seq.) in sjaecimens from the French coast and 

 from Algeria. 



Locality. St. Vincent, Cape Yerde Islands : growing on the 

 bottom of a lighter; 20th Jvily, 1904. Also found on 22nd 

 July, 1904, by diving among coral in a depth of 2 fathoms. 



MoNOST^CHAs quadridens (McCrady 1857). (Plate XXY. 

 fig. 4.) 



Two colonies have been referred to this species. They differ 

 markedly in size and habit from the flabellate, dichotomously 

 branched, 6-inch high specimens described by Nutting (1900, 

 p. 75) ; for they are unbranched and but 1 cm. in height. Never- 

 theless the minute structure agrees so closely with Nutting's 

 descriptions and figures, that I cannot regard these specimens as 

 specifically distinct. I noted, however : — (1) The peculiar manner 

 in which the hydroclades arise from the stem. The distal 

 pox'tion of the stem-internode bends over towards the antei-ior 

 aspect of the stem, and to the end of this bent portion the hydro- 

 clade is attached by a slanting node ; while from the posterior 



