416 Dr. E. 8. Morse on the Early Stages 



son and Prof. Verrill. The specimens were found attached to 

 stones brought up in the dredge, and also adhering to the 

 hnvcr valve of adult individuals, generally near the peduncle. 

 An examination of adult individuals showed that while the 

 ovaries in some specimens were empty, in others they were 

 fully charged ; in some the ovaries would be partially empty, 

 in others the ovaries of one side would be nearly empty while 

 those of the other side would be quite full. Specimens col- 

 lected by Prof. Verrill in August were foujid with eggs ; and 

 eggs were also noticed in specimens less than tliree six- 

 teenths of an inch in length. The eggs (PI. XA'. fig. 1) 

 were generally kidney-shaped, though very irregular as to 

 form and size ; they were spermaceti-white in colour, and 

 opaque, though having a central area translucent and appa- 

 rently depressed. In general outline they suggest the kidney- 

 shaped eggs of Fredericella. No intermediate stage was 

 observed between the ovarian ^^g and the stage represented 

 in fig. 2. This form recalled the general proportions oi Ar- 

 giojye and Megerlia^ in being transversely oval, in having the 

 hinge-margin wide and straight, and in the presence of a 

 pro])ortionally wide foramen. This stage was exceedingly 

 minute ; and only two individuals were discovered ; they were 

 attached to the rock, resting on the broad hinge-area. No- 

 thing could be traced of the structure, except an appearance of 

 granular contents, as indicated in the figure ; the shell showed 

 nothing of the scale-like structure so characteristic in later 

 stages. Between this stage and the next (fig. 3) the shell 

 rapidly elongates, while the hinge-margin remains nearly the 

 same in width ; this is also shown in the concentric lines of 

 growth seen faintly on the surface, indicating a rapid increase 

 in the length of the shell, Avhile no corres])onding increase 

 takes place in the widening of the hinge-margin. The pe- 

 duncle is longer than the shell, having distinct walls appa- 

 rently enclosing a clear interspace, the end slightly dilating 

 and forming a pear-shajied adhering disk. The structure of 

 the shell, of which more will be said in subsequent })ages, 

 showed clearly the scale-like structure, with the ca^cal tubules 

 of tlu! ])allial lobes ])erforating it. The anterior margin of the 

 paliial i(tbes gave rise to seven sett\3 of variable lengths, all of 

 them projecting forward. These seta?, in nearly all instances, 

 were clothed with Desmids, and were })robably available in 

 attracting sustenance to the animal ; they resembhnl in struc- 

 ture the setaj of the adult, as figured by Hancock; and the 

 longest of them was as long as the slioll. The future position 

 of tlie calcareous loop was iiidicatinl by a strongly arched 

 jtrocess midway the K^igth of the shell, tiom which sprang 



