1310 THE BUTTERFLIES OF NEW ENGLAND. 



degree ; the mesonotum bears a broad, triple ridged, but not very high pro- 

 jection, and the oeellar prominences are large, prolonged and divergent ; 

 the sides of the body are also ridged from one extremity to the other. 



EXCURSUS L.— DECEPTIVE DEVICES AMONG CATERPIL- 

 LARS, OR THE DEFENCES OF CATERPILLARS. 



Kriechend zaudre die Raupe, der Schmetterling eile geschaftig, 

 Bildsam iiudre der Menseh selbst die bestiramte Gestalt. 



Goethe. — Metamorphose der Pflanzen. 

 She creeps; 

 Her motion and her station are as one: 

 She shows a body rather than a life; 

 A statue, than a"l)reather. 



Shak^spbare.— Antony and Cleopatra. 



In a previous excursus some account was given of the protection en- 

 joyed by caterpillars of butterflies through then- coloring and theii' imitation 

 of natural objects, by which they escape detection. In the present we jjro- 

 pose to mention some of their means of defence against foes, due to their 

 actions or mode of life, actions which seem to be hereditary in precisely the 

 same sense and enforced by natural selection in quite the same way as are 

 the protective colors ; these creatures act, therefore, in some sense as auto- 

 mata, those caterpillars not availing themselves of these defences of their 

 forefathers being the first to be cut off, and so leaving no descendants to 

 inherit their individual propensities. 



The life of a caterpillar is full of perils from birth to maturity. Though 

 often formidable to look at, it is nevertheless soft skinned. Though it 

 may have a choice place of concealment or even a well constructed nest, 

 it must roam at large while seeking food ; and there are several periods of 

 its life, when, to undergo its ecdysis, it must remain an entire day or even 

 more, motionless and helpless and generally quite exposed. Its main jjur- 

 pose in life, next to feeding, is not to be seen. 



One of the simplest devices to escape notice is that of confining all ac- 

 tivities (which include with these gluttons scarcely an}i;hing but feeding) 

 to the night time and retiring to some concealment during the day. This 

 is a very common occurrence with the Satyrinae and Argynnidi in partic- 

 ular, the Argynnidi with their dusky clotliing retiring to the surface of 

 the ground where they are least liable to be seen, the satyrids remaining 

 perhaps upon the stems or blades of grass or sedge which form their food and 

 among which they are concealed by their striped attire. Or the retii'ement 

 may be to the under surface of a leaf, a very common practice, which is 

 exemplified in our own fauna by the habit, among others, of such diverse 

 butterflies as Polygonia faunus, Junonia coenia and Laertias philenor. 



A very common mode of concealment, however, is the construction of a 



