yoS Bashford Dean Memorial Volume 



The spiral flanges are narrow at the broader end of the capsule, and widen as they 

 approach the narrower end. 



Barnhart (1932) states that the egg case of H. francisci is about 120 mm. (4.7 inches) 

 long, and 50 mm. (2 inches) wide at its largest diameter, with two wide flaps running 

 spirally from end to end (as in his Fig.l). The si2;e varies, depending probably on the 

 age of the parent. I have no definite information concerning the egg cases of H. zehra 

 and H. quoyi. 



Before entering upon a somewhat detailed account of the structure and functions of 

 the egg capsule of Heterodontus japonicus, it seems desirable to examine some general 

 features of this capsule as a basis for comparisons with the other species already con' 

 sidered. Egg capsules of H. japonicus are illustrated in Text-figures 39 and 59 (page 752), 

 also in Figures 76 to 78, plate VII. These capsules appear to be stout-bodied, like those of 

 H. phillipi and H. galeatus— not slender like those of H. francisci. The width of the spiral 

 flanges is less than in H. phillipi, greater than in H. galeatus, and approximately the same 

 as in H. francisci. In the capsules of H. japonicus the two spiral flanges make comparative- 

 ly few turns about the body of the capsule : each flange encircles it from one and one-half 

 to two times. In the capsules of the other species considered, there are nearly twice as 

 many turns of the spiral flanges. In other words, in the capsule of H. japonicus the 

 spirals formed by the flanges are unusually loose. Since in this species the flanges are 

 only moderately wide, it follows that an unusually large amount of the surface of the 

 body of the capsule is exposed. 



The primary function of an egg capsule is of course protective, but provision must 

 be made for the aeration of the embryo and for its eventual hatching. The gross structure 

 of the egg capsule of Heterodoixtus japonicus, and its role in respiration and hatching, are 

 described in Dean's notes on which the following account is based. 



The capsule of H. japonicus (Figures 76 to 78, pi. VII,) varies considerably in sizie: 

 in length from 120 to 180 mm. (4.7 to 7 inches), and in weight from 145 to 238 grams, 

 including yolk and embryo. It is somewhat conical in shape, drawn to a point at one end 

 (''lower", distal or "vegetal") but to a "chisel-like" edge at the other ("upper", proximal 

 or "animal"). It is provided with two marginal bands which encircle the capsule spirally 

 somewhat as the "thread" surrounds a screw. These bands arise at the sides of the upper 

 or broad end of the capsule, and are homologous with the marginal bands which occur in 

 the egg capsules of many sharks and chimaeroids. But instead of passing straight down- 

 ward, they wind about the capsule two and a half times (according to Dean's notes) 

 until they terminate with short processes at the lower end. Here the spiral bands are 

 wider and are more nearly transverse. The freshly deposited capsule is dark bottle-green 

 in color, as shown for the first time in Dean's drawings (Figures 76 to 78, pi. VII). Later 

 the capsules become paler, brownish or sometimes ochreous. Altogether they resemble 

 certain large cysted brown sea-weeds, but whether this resemblance is a protective one 

 is not known. 



