OP ARTS AND SCIENCES. ' 69 



Stage V. and last. — Length 45-50 mm. In its final shape, the 

 body is cylindrical, tapering towards each end, and not so stout and thick 

 as in Platysamia, or Telea, or Actias, or Attacus, and the tubercles are 

 smaller, smoother, and without the conspicuous large spines present in 

 the genera named, while the dorsal abdominal tubercles are smaller 

 than in any other genus of AttaciniB known to us. In its larval char- 

 acters the genus is the last and most specialized of a series beginning 

 with Saturnia {S. carpini) and including Platysamia and Samia. 



The head is small, being a little less than one half as thick as the 

 body, and now is without any black spots. The black dorsal protho- 

 racic and abdominal tubercles are much shorter than in Stage IV. The 

 dorsal prothoracic ones are mere black spots, not even rising into low 

 warts ; the two lateral ones on each side are much larger than the 

 rudimentary dorsal ones, rising into low conical shining black tuber- 

 cles no hisher than wide. The homologous lateral tubercles on 

 thoracic segments 2 and 3 are larger and more prominent than those on 

 abdominal segments 1 to 7. The rudimentary black dorsal tubercles 

 on abdominal segments 1 to 7 are low rounded conical shining black 

 bosses, which are transversely oval at base, and not so high as wide. The 

 four dorsal 2d and 3d thoracic tubercles, together with the single 

 median one on the 8th abdominal segment, are all of the same size seen 

 sideways, but the last named tubercle seen from in front or behind is 

 thicker, owing to its double origin. The two dorsal ones on the 9th 

 abdominal segment are rather high, being long, conical, but no higher 

 than the median single one on the 8th segment. All the legs are yel- 

 lowish ; each of the middle abdominal legs with a black dot in the 

 middle of the outer side. 



Professor Riley has briefly described and in part figured in his Fourth 

 Missouri Report (p. 121) the five stages of this larva; and my ma- 

 terial confirms his description. Mr. Dyar, however, claims that from 

 his observations there are but four stages. For the colors, since we 

 have not yet seen the living larva, we must quote from Riley, who 

 states that in the fifth stage " the appearance is totally changed ; the 

 body is of a most delicate bluish white, with a faint pruinescence." 

 Further on he says : " As this worm acquires its full growth, the prui- 

 nescence mentioned above disappears, and it acquires a more greenish 

 cast, except around the base of the tubercles, where there is a more 

 decided blue annulation." In Psyche for June, 1891, M. Beuten- 

 miiller gives a detailed description o{ six stages, Jive moults. His fifth 

 and sixth stages appear to be the same as our fifth. 



