266 MEMOIRS NATIONAL ACADEMY OF SCIENCES. vol. xii, 



It is probably significant that in these complicated crosses the hybrid is always the male 

 parent. 



The most remarkable cross made by Standfuss was Saturnia pavonia-minor o* X GraeUsia 

 isabellse ? , but it could not be raised to maturity. 



(For details concerning the work of Standfuss, see Proc. Seventh International Zoological 

 Congress, published at Cambridge, Mass., 1912, pp. 111-127.) 



Mr. J. II. Watson (Nov. 2nd., 1912) has described a hybrid between Caligula japonica and 

 C. simla, obtained under experimental conditions. Two female moths secured were both 

 sterile.] 



PHTLOSAMIA CYNTHIA [i. e., WALKERI] o* X CAIXOSAMIA PROMETHEA ?. 



Plate LXXI. 



Larva. — Stage III: Length 1.5-17 mm.; head 2\ mm. in width, with two black bands 

 separated by a straw-yellow one. Five larvse molted July 29-30. 



Body now more white and covered with a white powder. In all of them the black stripes 

 are present, but not quite so wide as before. The four thoracic and the eighth median dorsal 

 tubercles much larger than the others and bright lemon-yellow, as are the end of the abdominal 

 median and anal legs. It differs from my description of C. promethea in the black rings being 

 present, two on each segment as before. The curved black line on the outside of the anal legs 

 boomerang-shaped or crescentiform. Two dusky dots on each side of the midabdominal legs. 

 The black curved spot on the suranal plate is as in stage II. In two of them the second thoracic 

 dorsal tubercles are black, so that there are only two lemon-yellow thoracic tubercles. 



Stage IV: Molted again August 4. Length 17-18 mm. 



Head yellow, black across in front of the clypeus, with a black dot on each side, back of 

 the head toward the occiput black. Now there are no black bands, the four thoracic dorsal 

 tubercles are high, deep orange and black at base, the median tubercle on eighth abdominal 

 segment greenish-yeUow. All the other tubercles black. Suranal plate with two large black 

 tubercles, behind which the surface of the plate is orange; end of the plate with a transverse 

 black line. On the outside of the anal legs a long narrow, much curved black fine, much nar- 

 rower, more linear, than in stage III. 



The body is now whitish, the lunder edge of the abdominal segments greenish. (It died 

 after molting; agrees exactly with my description of C. promethea, stage TV.) 



[The following from Herman Strecker (litt., 1900) requires further elucidation:] 



"You know cynthia crosses with promethea, but the product from the act being done in a 

 state of nature is widely different from that produced by pairing in confinement or by artificial 

 inducement. The first is a curious thing; color of cynthia, with discal marks [and] shape of 

 promethea 9 . Those bred in confinement produced tilings ( o* ) looking like 9 of promethea 

 nearly, only blackened, not reddish." 



PHILOSAMIA HYBRIDS. 



Plate XCIII, figs, j, k, 1, m. 



Watson, Wild Silk Moths of the World (1912), PI. III. 



[The species of Asian Philosamia interbreed with one another and produce fertile hybrids. 

 During the last two or three years I have produced hybrids of vesta, which used to be reared 

 extensively in France 40 years ago. This is the result of P. walkeri (China) X P. ricini (Hutt) 

 (Bengal and Assam). This hybrid as reared by myself has two distinct forms; form vesta 

 partaking of the ricini side (some specimens of which I have seen in Mr. Rothschild's collection 

 from the Elwes collection) and a form which I have named russelli, after Dr. Russell, of Lincoln, 

 who has reared it at the same time as myself. It approaches in appearance more to walkeri 

 and is a well-marked mutative form. It, as well as the vesta form, may be transmitted to other 

 generations. 



