122 Transactions of the Royal Canadian Institute, [vol. x 



The extrusion of the egg causes it to become elongated; the greater 

 axis may be almost twice the less. In the case above noted the spherical 

 form was assumed within a few minutes; in other cases the elongation 

 has taken more than an hour to disappear. Exceptionally the elongated 

 form may be retained for a considerable time. The most extreme case 

 met with was an egg found among natural surroundings with the longest 

 axis 5.25 m.m. and the shortest 2.75 m.m. In the same cluster was 

 another elongated egg, its axes being 4.0 m.m. and 3.0 m.m. The three 

 remaining eggs were spherical; all five were in the process of gastrulation. 

 Another egg, quite similar to the one first mentioned was laid by a female 

 in a terrcLrium ; it kept pace in development with the remaining eggs of its 

 cluster up to the 50-60 cell stage. In the first two cases the segmenta- 

 tion cavity had formed near one end of the long axis, in the third case 

 near one end of a short axis. As the eggs were fixed at the stages men- 

 tioned it s impossible to say how the further development would have 

 been affected. 



This mode of egg-laying places Plethodon at the end of a pro- 

 gressive series, the most primitive member being Cryptobranchus, with 

 eggs laid in a uniform rosary-like string as described by Reese (1904) 

 and Smith (1906). Next, as suggested by Wilder (1913), would stand 

 Desmognaihus; in this genus most of the eggs have left the man string 

 of the rosary and lie at the sides of it, each retaining connection with it, 

 ^ ; however, by a short stalk. The next step is represented by such a case 



as Spelerpes (Wilder, 1899) or Antodax (Ritter and Miller, 1899); here 

 the disappearance of the main string leaves each egg to be attached 

 separately to its support — usually a stone — by a short stalk. The 

 disappearance of this stalk for each egg, except the first, produces the 

 separate eggs of Plethodon. This economy of material is highly desirable 

 in so small an animal. The position of Antodax in the series given above 

 is not that usually occupied by the genus in a series that shows progressive 

 modification of some primitive habit; in most respects Antodax has 

 departed furthest from the primitive amphibian mode of life, and Pletho- 

 don can only offer suggestions as to the path along which Antodax has 

 travelled to its present condition. In habits, however, as in morpho- 

 logy, it does not follow that the higher member of a series must in every 

 point have progressed beyond the lower. 



Other observations differing from the foregoing are as follows: 

 Case II. In examining a terrarium on one occasion there was un- 

 covered a female that had evidently just completed the extrusion of the 

 «gg8' Two eggs, approximately spherical, were in contact and cohering 

 slightly; four other eggs, each more or less elongated, were lying separ- 

 ated from each other by intervals of about one-quarter of an inch ; none 



