444 NOTES ON PH0S015KANCIIIATA, 



The capsule mass is oval in transverse and longitudinal section; 

 its dimensions are 155 x GO x 50 millimetres, and was apparently 

 attached by one end; it contains about eighty individuals, all with 

 their apices turned outward and their anterior canals towards 

 the centre. 



As far as may be judged from young specimens of M. indicus 

 at my disposal, the shell of J/. diadenKc when it bursts the capsule 

 is similar to those on which Mr. Woodward founded his remarks. 



Specimens which entirely fill their respective capsules consist 

 of a protoconch of three and one-half whorls, and one-half whorl 

 of adult structure. Such a specimen measures 28 mm. in length 

 and 16 in ))readth, the length of the aperture being 21 mm. The 

 crown of the spire is liat, the nucleus being slightly depressed. 

 The protoconch is very faintl}' defined from the succeeding 

 structure by the possession of obsolescent revolving lirse, and a 

 slight and somewhat abrupt thickening of the shell. It is pro- 

 bable that this protoconch was cast inside a horny original, which 

 was discarded at an earlier stage than I have been able to study. 



Dr. Dall* was able to demonstrate that the protoconch of 

 Scaphella mayellauica, Sby., was cast inside a horn}^ original. 



This calcareous cast of a primitive horny shell, when it has 

 been deposited subsequent to the veliger, is in the following- 

 pages designated the pseudo protoconch, in contradistinction to 

 the true protoconch, which was secreted previous to or during 

 the veliger. Many true protoconchs are, however, calcareous, as 

 for example those of the various species of Triphora. 



The SHCcession of the coluniellar folds. — Before proceeding to 

 discuss the definition of the nepionic stage, it will bo in order to 

 draw attention to the sequence of the acquisition of the coluniellar 

 plaits. This is of particular interest, as being in perfect con- 

 formity with Dr. Dall'sf phylogonetic scheme of their origin, 

 viz.: — The first to appear is the anterior, and the last the posterior, 

 this last being subsequently aborted. The anterior, which in 



* Dall, Bull. Mus. Comp. Zool. Harvaid, xviii., 1SS9, p. 4,52. 

 t Dall, Wagner F. Inst. 8ci. iii., pt. 1, 1889, p. 58 et seq. 



