ONTOGKNY OF IvARVAI, COI.OR PATTE^RNS. I43 



ical colors are rare and chemico-physical of no great importance. The color 

 patterns, therefore, are largely pigmental, although to these may be added a 

 few instances of the specialized categories of color in the more specialized 

 species. As far as the colors themselves are concerned this genus exhibits a 

 full development of pigmental coloration, with the earliest stage in the devel- 

 opment of the more highly specialized physical and chemico-physical. 



THE ONTOGENY OF COLOR AND COLOR PATTERNS. 



IN THE IvARV^. 



The ontogeny of larval or youthful ornamentation in animals has received 

 little attention from zoologists, although most interesting, suggestive, and con- 

 clusive data may be obtained from this source. Paleontologists, especially 

 Hyatt and his pupils, have obtained some notable results from their studies 

 along this line on fossil organisms. 



I have shown in a former paper that the color patterns of insects are of 

 segmental origin and that the various spots and stripes are in all probability 



S> O a 



T3 SOB 



PI S 



.S * o 



'•- O m 



anterior and posteriox 

 bands of tergal spots 

 upon abdominal 



posterioT pronotal band «s E i- segments 



ftnt.exior pronotal liand 



I 



I 



a)OViter.ioi lateral epicranial^ | I } 1 { I { [ ' ji<''<?T''\3?Tf|^ tergals 



^v J*^\' ' ' ' 'l<^r\'i''\*''i l-^'Wr" —.middle tergals 



*■* ' ■' * ' ■' .«— outer tergals 



antericr lateral epicranial. «. .^J(|B^P_'.i^(^j'/i^l''^;l 'Y\\'y\}:P^'i^ — spiracula spots 



,,_ —,. . ,.__ .— ,i_v, .w-i^.^^. ,.- -T ^„ . „..|, baso-plenral 



antennary_£^ai>-:r(»^W^A^^^Sg^^^^^^ outer sternals 



gular.— p3l^^^^^3Br^^"^^A^NrNy\Af/7^^ ~ — middle sternals 



(/prothoracic epiraculac j '| j spiraculaf, l to V baso-pleuraUabd) 



I I metathoracic wing spot- 



i mesothoracic wing spot 

 baso-ploural (thoracic) 



TEXT-FiGtJRE 7.— Diagrammatic representation of the centers of color development 

 found in the young larvse of Leptinotarsas. Drawn from a young larva of L. unde- 

 cimli7ieata,a.ii seea in side view. 



directly derived from modified or combined, segmentally placed centers. In 

 Leptinotarsa this idea has been put to a most exact test with the result, as will 

 appear in the following pages, that it appears to be in all respects valid. 



In the young larvae of very many Chrysomelidae, Coccinellldse, Cassid^, and 

 other forms is found a system of color centers which is highly suggestive and, 

 as we shall see later, ideal in its simplicity. In late embryos or newly hatched 



