222 DR. CARPENTEll'S RESEARCHES ON THE FORAMIN1FERA. 



obtuse angles is shown in fig. 6, and that of the acute in fig. 5 ; and in each view it is 

 seen, that the divergence takes place in a plane which passes through the common 

 centre of all three. The specimen delineated in fig. 10 exhibits a multiple outgrowth 

 of a nature resembling that shown in figs. Sand 9. For from the surface of the disk 

 there rises a triradiate crest, formed by three vertical plates meeting one another at 

 nearly equal angles, but all of them nearly perpendicular to the plane on which they 

 rest. It is a very remarkable feature in this specimen, however, that the line in which 

 the three vertical planes meet, is traceable at its base to the nucleus of the horizontal 

 disk ; so that they all bear the same relation to it, as does the single outgrowth in the 

 instances previously cited. Hence we may attribute all these monstrosities to an 

 excess of productive power in the sarcode of the original nucleus, which has put forth 

 its first extension, not merely in the horizontal, but also in the perpendicular direction ; 

 the whole subsequent development of these outgrowths taking place after the normal 

 plan, from the foundation thus laid. It is interesting to remark, that the presence 

 of such outgrowths as those now described, is far more frequent in certain localities 

 than it is in others. Among some hundreds of specimens which I have examined from 

 the coast of Australia, I have only met with those represented in figs. 7, 8, 9, and two 

 or three others ; the remarkable specimen delineated in figs. 5, 6, occurred with 

 another less peculiar among a comparatively small number of Orbitolites collected 

 by Mr. CUMING in the Philippine Seas; but in a small collection which I have 

 inspected from the ^Egean Sea, the monstrosities of this kind (of which fig. 10 was 

 the most remarkable) were so numerous, that I think I am scarcely wrong in assert- 

 ing that one specimen out of every three or four presented some excess*. Among 

 the fossil Orbitolites of the Paris basin, the presence of a completely-semicircular vor- 

 tical plate is not at all uncommon. 



63. There may be some doubt in the first instance, as to the light in which we are 

 to regard the specimen represented in Plate VIII. fig. 10; whether as a ' monstrosity 

 by excess,' or as the product of the fusion of two individuals : but I think this will be 

 removed by a closer examination. For it is obvious, that the smaller disk, which is 

 surrounded by the outer zones of the larger one, has been developed from a nucleus 

 of its own ; and this nucleus does not appear to have any direct connexion with the 

 periphery, still less with the centre, of the larger disk : on the other hand, when we 

 consider the circumstances under which Orbitolites grow (^[ 34.), it is very easy to 

 understand, that the smaller and younger individual, having attached itself in too 

 near proximity to the larger and older one, should become imbedded therein (so to 

 speak) by the extension of the newly-forming zones of the latter around its margin. 



* This is by no means a solitary case of the prevalence of monstrosities in particular localities. The collec- 

 tion of Mr. BEAN of Scarborough contains a number of curiously- distorted specimens of the common Planorbis 

 marginatus, -which have all been collected in one brook. Their peculiarities are by no means repetitions of each 

 other ; and I am disposed, therefore, to regard them rather as resulting from the influence of external condi- 

 tions, than as accidental varieties hereditarily propagated. 



