40 



THE AMERICAN NATURALIST [Vol. XLIII 



obtain it in our own species have failed. In 

 er dies at this stage." His Fig. 25 is Huxley's 

 . Figs. 1, 2 of PI. XXIV are Jackson's own 



diile it was a free larva. The figu: 

 mgnified 120 diameters the actual 1 

 fixed spat, was nearly .31 mm. 

 Prince (13, 13) makes the statem 



McBride (14, 151, 153) says: "Judging from the size of free-swimming 

 larvae caught by the tow-net .... During the latter part of the month 

 (August) the waters were swarming with larva? which, from their exact 

 agreement in shape and appearance with the larvae of the European oyster, 

 were doubtless the later stages of the free-swimming young of the Malpeque 

 oyster. . . . The later larvae which were captured by the tow-net are 

 characterized by possessing a straight hinge to the shell. . . . Fig. 4. Late 

 Larva of the Oyster captured by the Surface-net." The so-called late 

 larvae are in the light of my researches in reality somewhat early larvae. 

 Late larvae would be more appropriately applied to the umbo-stage which 



the latter part of August were swarming with young straight-hinge oyster^ 

 larvae does not correspond with what I found at the same place the succeed- 

 ing year. Upon examining Fig. 4 I find that it is not an oyster larva. 

 The measurements are 83, 70, 51 mm. which if divided through by 5.53 

 will give 15, 12.6, 9.2 mm. as the length, height and hinge-line. Eeferring 

 this to the table of comparison of a mussel, a clam and an oyster at thia 



s-Duthiers (1, 105) said: 



Horst, 



1 fl""' 1 '' 



pen saillant simule un rudiment de pied." Horst (2, 162) 



likeness to a young gastropod." Brooks (5, 53) wrote: "Near the center 

 of the ventral surface— the top of Fig. 32— there is a well-marked and 

 constant protuberance of the body wall, which occupies the region which, 

 in most molluscan embryos, gives rise to the foot, and which may perhaps 

 be^ regarded as a rudiment of that organ." In the same paragraph and 



and on page 68 "the primitive digestive tract opens by a wide blastopore." 



