144 
MEMOIRS OF THE jS^ATIONAL ACADEMY OF SCIENCES. 
ACQUIRED LARVAL CHARACTERS. 
Tbe two subdorsal yello^tisll longitudinal strii)es ])rol)ably appear at tlie end of tlie second stage. 
In Stage III tlie whitish bloom appears. In Stage IV the suranal plate is edged with yellow. 
This is, next to simplest, least specialized Notodontian larva; more so than 
that of Lophodonta, The body is without tubercles or huin]>s; the jiiliferous warts are minute and 
the simplest markings are colorational, i. e., two yellowish siibdorsal bands, with no spots. In the 
Notodontians the subdorsal lines are the first to appear, before the lateral ones. 
Tiie following is a copy of an article entitled ^‘The number of larval stages in the genus 
Nadata,^' by Mr. Harrison G. Dyar, Psjxhe, October, 1802, which we reproduce, as it gives a full 
account of the transformations of this si)ecies in California, and contains interesting notes on the 
habits : 
111 Psyche, recently, 1 expressed the opinion that species oi Xadaia had more than six larval stages, which was 
founded on certain nieasnrenisnts made from Kadata (jibbosa. I have not since obtained this species in the early 
stages, ' hnt have bred another from the egg, which is A*, oreffonensis Cutl. lu this species, the number of stages 
appears to be normally six; hut two individuals carefully bred in coufincmeut and two bred iii the open air had but 
five stages, wbilo another spociuicu, less carefully reared iu confinement beside another bred in the open air on its 
growing food plant under a net exhibited six stages, but not the uoriiial ones. All the larvje ajipeared to omit the 
normal second stage, even those that had six stages. These latter inserted an extra stage between the fourth and 
fifth, not diftering iu inarkiiigs from the fourth, as will be seen iu what follows. The growth during the first stage 
was very groat, out of all proportion to the snbserpient growth, and, jirevions to molting, the new head, in process 
of formation behind the old one, caused an enormous projection of the body. 
The calculated normal series for the widths of bead stands as follows: I, 0.79 [II, 1.13] ; HI, 1.62; IV, 2.31; V, 
3.3; VI, ‘1.7 mm. ; ratio, 0.70 mm. 
From the larvje that had live stages I obtained the following measurements: First, 0.75; second, 1.55; third, 
2.35; fourth, 3.3; fifth, 4.7 nvm. 
From those that had six stages — first example : First, — ;* second, 1.4 ; third, 2.2; fourth, 2.7; fifth, 3.2; sixth, 
^inm.3 Second example: First, — second, 1.5; third, 2.3; fourth, 2.8; fifth, 3.7; sixth, 4.8 mm. 
It will bo seen that in the first oxumple an extra stage occurred between the normal Stages IV and V, and this 
is verified by tbe changes in markings; for in those that had five stages, the markings changed in the fourth stage, 
while in this the fourth stage was like tbe third and the change did not occur till the fifth stage. 
In the second example the fifth stage was ahnonually large, so much so that the last four stages in this case 
present a good series with the ratio 0.77, and, judging from these stages only, it would certainly ho inferred that 
the species had eight larval stages, ^ with the following series of widths of head (calculatcMl) : 0.77, 1.0, 1.3, 1.7, 2.2, 
2.8, 3.7, 4.8 mm; ratio, 0.77 nim. Compare with this the last four niensurementvS of the second example. 
The species of Nadata, then, present examples of variation in the number of larval stages, as well as an 
abnormal development. 
It is probable that Edema aUncosta acts in a similar though less x>rononnced manner.^ 
The following descriptions apply to the species of Nadata that is common in the Yosemite Valley, California. 
^ Miss Soule has recently written the life liistory of X. gihbosa (Psyche, v. 6, 197) and found live stages, as did 
also Dr. l?iley (see 5th Rex)t, U, S. Eut. Com., 1890). Ibi fortunately, Miss Soule has given no measurements of the 
head, hut she has given the length of the larva iu all its stages, and the numbers she gives correspond well with a 
series derived with the ratio O.fiO. This docs not corroborate my observations (on X. oregonenHis), as to do so a stage 
should apjiear lacking between Stages I and II, provided that tlie measurements were made at the first of each stage. . 
Miss Soule’s figures aro*3.1G (=19), ^ ( = .2o), | ( = .50), | ( = .75), and IJ ( = 1.25) inches, while the calculated series 
would be .15, .27, .45, .75, 1.25 inches, thus showing no gap in the series anywhere. To suit my observations the 
newly hatched larva should have measured 0.10 inch instead of 0.16 inch. Miss Soule says “not quite inches,’’ 
which is certainly nearer 0.15 than 0.10, as tho latter would bo not quite ^ inch. 
But I do not think the length of the larva is a reliahlo measurement to take, as it is subject to great change 
throughout the stage, and, even if taken as nearly as possible at tho same time in each stage, is subject to inaccu- 
racies through tho expansion or contraction of the larval segments. Moreover, it tiik(‘S no account of the growth 
during cither the first or the last stage, according as the measurements are made at Iho end or beginning of each 
ptage, and 1 should hesitate to assume that tho growth was always strictly proportional. Inflict,! believe that 
in Nudata it is not so, for double growth seems to take place iu tho first stage. 
Tho measurement of the width of head is open to none of the above objections and jiossesses besides several 
advantages not shown by iiieasurenicnts of the length of tho larva. 
2 Measurement not recorded. 
^This larva died ludbre molting tho last time. 
•*From similar ineasiiremonts made iu the case of X. gibbosa^ I inferred that that species had more than six 
Btages (see Psyche, v. 6, p. 147), but this inference is not justified by the facts. It will be found, however, to have 
occasionally as many as six stages. 
'■'The series of widtlis of head as observed by me for Edema aJhicosta were 0.40, 0.70, 1.30, 1.7, 2.3, 3.2, and I have 
twice atteinjited in the jiages of Psyche to make them fit a series iu regular geometrical progression, hut without 
