parasitic on Hydromedusce at St. Andrews. 259 



thus constituting a type of muscle very different from the 

 reniforra section of the retractors in Halcampa. My material, 

 as I have previously said, is insufficient for me to pronounce 

 an unqualified opinion, but there is nothing in the cha- 

 racter of the longitudinal muscles of the mesenteries antago- 

 nistic to the view that these are the larvaa of Peachia hastata. 

 The latter species, according to Prof. M'Intosh (6), is common 

 in the neighbourhood. I would further point out that the 

 St.- Andrews larvae, stage for stage, are decidedly larger than 

 those of the Halcampa which occurred to me ; this would 

 also correspond with the greater size of the adult Peachia as 

 compared with that of Halcampa. 



According to Prof. Verrill (7), the young of an American 

 species of Peachia is parasitic in the lip-folds of Cyanea arc- 

 tica. Prof. M'Intosh quite recently published a note on our 

 form, which he assumes to be the larva of Peachia hastata^ 

 without, however, adducing any evidence in favour of his 

 supposition, except the statement that the adult is very com- 

 mon. The parasitic actinian certainly appears to be not at all 

 unfrequent. So far as my evidence goes, it supports, but 

 does not prove. Prof. M'Intosh's conclusion. 



List of Papers referred to in above Report. 



(1) A. 0. Habdon. — " Note on the Arrangement of the Mesenteries in 

 the parasitic Larva of Halcanqm chrifsmithellum (Peach)." Proc. 

 Roy. Dublin Soc. (n. s.) v. 1887, p. 473, pi. xi. 



(2) T. S. Weight. — " Observations on British Zoophytes. On Peachia 

 Fultoni, a parasitic Actinia." Proc. Phys. Soc. Edinb. ii. 1859, p. 91 ; 

 New Edinb. Journ. xii. 1860, p. 156;' Ann. & Mag. Nat. Hist. [3] 

 viii. 1861, p. 132. 



(3) A. C. Haddon. — " Revision of the British Actiniae. — Part I." Trans. 



Roy. Irish Acad. 1888 {in the press). 



(4) A. C. Haddon. — " Note on Halcampa chrysantheUum, Peach." Proc. 



Roy. DubUn Soc. (n. s.) v. 1886, p. 1. 



(5) A. C. Haddon. — ' Actinozoa ' in " First Report on the Marine Fauna 

 of the South-west of Ireland." Proc. Roy. Irish Acad. (2) iv. Sci. 

 p. 616. (See also Trans. Roy. I. Acad. 1888.) 



(6) W. C. MTntosh. — "Invertebrate Marine Fauna of St. Andrews." 



Ann. Mag. Nat. Hist. [4] 1874, xiii. p. 220. 



(7) A. E. Vebbill. — " On the Polyps and Echinoderms of New 



Eno-land." Proc. Boston Soc. Nat. Hist. x. 1866, p. 338 ; also in 

 Rept. U. S. Fish Comm. i. (1871-72), 1873, p. 739. 



(8) W. C. M'Intosh. — " Notes from the 3t. Andrews Marine Laboratory 



(under the Fishery Board for Scotland). — No. VII. 3. On the Com- 

 mensalistic Habits of the Larval Forms of Peachia.''^ Ann. Mag. Nat. 

 Hist. [5J 1887, XX. p. 101. 



