240 



Prof. P. M. Duncan on Thallophytes 



after I had become engaged in these investigations. He writes*; — 

 " Vegetcible Parasites. The corallum of both Milleioora and Pocillopora is 

 permeated by fine ramified canals, formed by parasitic vegetable organisms 

 of the same nature as those described by Dr. Carpenter and Prof. Kolliker 

 as occurring in the shells of moUusks &c. The organisms were found in 

 abundant fructification; they were gi-een, but otherwise appear to be 

 fungi, as are the parasites of shells &c. Similar parasites are to be found 

 in various eoralla from widel}^ distant parts of the world." 



The paper communicated by me to the Geological Society " On some 

 Dnicellular Algse parasitic within Silurian and Tertiary Corals, with a 

 Notice of their Presence in Calceola sandalina and other Possils,"' was 

 read Jan. 19, 1876 (Quart. Journ. Greol. Soc. vol. xxxii. p. 205). 



II. The Range of the Parasites^ and a List of Sjpecies e.vamined. 



Both KoUiker and Mr. Moseley have sho^^-n that corals from different 

 localities and belonging to widely remote seas are affected by the parasitic 

 organisms. 



Having found the ramifying tubules and their contents in the corallum 

 of Flahellum laciniatum, Edw. & H., from the neighbourhood of Davis 

 Straits, at a depth of 380 fathoms, and in Balanoj)hyllia verrucaria, Pallas, 

 from the Mediterranean, at different but not great depths, the previously 

 kno^TL rauge may be thus increased. All the deep-sea corals examined 

 from the bed of the Xorth Atlantic are more or less affected by the 

 parasite, and the littoral forms also. Thus in Cargojjhyllia davus, var. 

 horealis, from a depth of 1 to 30 fathoms, in Loj)hohelia j^'^oUfera, from 

 422 fathoms, and in Solenosmilia variahilis (nobis), froui 1095 fathoms, 

 the tubes were found in greater or less abundance. 



The specimens examined by Ivolliker and Mr, Moseley were mostly from 

 seas with a high temperature ; and the s^^ecie^ of coral to which reference 

 will be made in this communication were located during their lifetime in 

 temperatures from 39*^*7 to 55° Pahr. The bathymetrical rauge of the 

 unicellular parasite is therefore from low-water mark to 1095 fathoms 

 in the northern seas ; and the temperature to which it is subject varies 

 from 39°- 7 to that of the surface water. But it is evident that it is the 

 most destructive when the pressure is least and the warmth of the sea is 

 greatest ; and therefore corals of genera such as Caryophyllia and Bala- 

 noj^hyllia, which are grown in aquaria, exhibit the parasite in per- 

 fection. 



The range of the coral-parasites in time, whilst admitting that there 

 may be and may have been more than one species, is very great. They 

 may be found in Upper-Silurian corals and in those of later date down to 

 the Tertiary tim.es; and tubular excavatious correspondiug in their 

 appearance may be found in some calcareous fossils of the Lower 



* Proc. Eoy. Soc. Kor. 26, 1875, vol. xxiv. p. 64. 



