134 Prof. P. M. Duncan on the Growth and [Apr. 12, 



pJiyllum Crista- Galli of different sizes and of many bush-shaped coralla 

 of Lojphohelia prolifera, var. gracilis ; there were also small masses of 

 iSolenosmilia variabilis (nobis), a new Amphihelia, and a specimen of 

 CaryojpliyTlia cylindracea (Reuss), which were not attached, but which 

 must have been fixed close by to stones. 



As the date of the sinking of the cable was known, and as six years had 

 elapsed, it was possible to estimate the rapidity of the growth of the coral 

 on it, and also to come to some more or less satisfactory conclusions re- 

 garding the rate of the deposit of the foraminiferal ooze in that situation. 

 Moreover a glance at the numerous specimens showed that they presented 

 variations and abnormalities of structure well worthy of examination, and 

 which might relate to the inadvisability of retaining some of the specific 

 and generic determinations in the ancient and recent coral faunas. 



The height of the tallest* Desmopihyllum taken from the top of the 

 cable, to which its base is strongly adherent, is If inch. It is a fine and 

 well-grown individual, being inch in its calicular length, and its hard 

 part weighs -i- oz. There are no indications of ooze having covered the 

 base, and the granulation of the basal surface is perfect and free from 

 any evidence of erosion. 



The smallest specimen found on the cable has its calicular edge rather 

 on one side and oblique, and it is -f^ of an inch above the attached base. 

 It shows no trace of ooze ; the other specimens, intermediate in size, 

 usually present an excessively broad base below the peduncle, and in some 

 it extends for nearly J inch on all sides. It consists of a layer of car- 

 bonate of lime, granular above and attached below to the outer coating of 

 the cable. 



Stunted bush-shaped masses of Lopliohelia adhered by broad bases to 

 the cable, and extended along it for many inches. The corallites com- 

 posing the masses were crowded together to the height of an inch from 

 the cable, and a few reached upwards about f of an inch above the 

 rest. Some had grown up obliquely, and others had their calices turned 

 downwards, so that their margins were not ^ of an inch from the cable. 

 They must have always been above the ooze. 



Gemmation appears to have occurred four times in the tallest corallites, 

 commencing on the parent when it attained a certain size ; probably the 

 parent growth occupied one year ; and there were four consecutive yearly 

 buddings. 



From these details it may be gleaned that the upward and general rate of 

 coral growth at 550 fathoms is rapid in relation to that noticed in Europe 

 in the same family in shallower water. In height the growth amounts to 

 a minimum of 029 inch in the year, and in mass it is very considerable. 



The amount of sedimentary deposit, consisting of the tests of Forami- 

 nifera, sponge-spicules, and minute particles of siliceous minerals, has been 



* The Desmophylla and Lophohelics are essentially oceanic deep-sea corals ; they have 

 none of the exotheca which distinguishes the rapidly growing littoral reef-building forms 



