970 PROF. J. p. McMURRICH ON 



as Halcampa medtisopMla, occurring on various medusse {Tima, 

 Oclorchis, and ^Uquorea) is proba,bly identical with Midler's 

 species, the absence of a conchula being probably due to its 

 greater immaturity. 



In 1860 Wright described as Peachia fultoni* a form that 

 he found parasitic on a species of Thaumantias (^Phialidium ?), 

 later (1861) changing its nnme to Halcamim faltoni. This is 

 probably the same as the form described by Haddon (1887), and 

 erroneously, as has been pointed out by Oarlgren (1904), regarded 

 by that author as the larva of Halcampa chrysanthellum. In 

 1887, Mcintosh recorded the occurrence of actinian larvse on 

 vai-ious Thaumantiad medusse occurring at St. Andrews, identi- 

 fying them as the young of P. hastaia, an opinion in which 

 Haddon (1888) concurred after an examination of their structure, 

 still maintaining, however, their distinctness from the examples 

 previously described as the young of H. chrysanthellimn. They 

 possessed eight tentacles and eight large mesenteries together 

 with four smaller deuterocnemic ones. It may be that Haddon 

 is correct in regarding the two forms he examined as distinct 

 species, but even if so it seems clear that they are to be referred 

 to the same genus, and since it is still uncertain that they 

 actually do develop into Peachia, it will be preferable to place 

 them in Bicicliimi. 



Finally, Dendy (1888) has described from medusee obtained 

 at Port Philip a parasitic actinian with twelve tentacles, within 

 which there was " an inner circle of 12 cushion-like swellings," 

 which in older individuals become saccular outgrowths. It is 

 not possible to ascertain from Dendy's account, whether or not 

 these outarowths repi-esent a conchula, and the exact affinities of 

 the form must remain doubtful, although with a probability that 

 it represents a Peachia'f. 



The available evidence seems, accordingl}^ to point strongly in 

 favour of these various medusophilous forms being young stages 

 in the development of Peachia rather than Halcampa, but a 

 direct linking up of the immature examples of Plcidium with 

 their respective adults is necessary to settle the question. 



* Some confusion exists in the references to the literature of this species. Andres 

 (1883) gives the date of its first description as 1859 and as references the Pro- 

 ceedin;TS of the Physical Society of Edinbnrg-h, vol. ii. 1859, and the New Edinburgli 

 Philosophical Journal, vol. xii. 1860. Haddon (1887) repeats the latter reference 

 but substitutes for the former, Proceedings of the Royal Society of Edinburgh, 

 vol. ii. 1860. There is no paper in the Proceedings of the lloyal Society of 

 Edinburgh by Wright referring to this species, and the date of vol. ii. of the 

 Proceedinn-s of the Royal Physical Society of Edinburgh, which does contain such 

 a paper, is 1861 and not 1859. The reference to the Edinburgh New Philosophical 

 Journal (this being its correct title) should read " New Series, vol. xii. 1860." 



t Carlgren (1904) mentions, without descriptions or names, two additional forms 

 that should probably be referred to this genus, one occurring in the medusa 

 Eufimalphes indicans on the Swedish coast and the other ou a large medusa from 

 Valparaiso. 



