148 PHOSPHORIC INSECTS. 



United States. The species described by Illiger 

 (in vol. i. of Annals of Nat. Hist. Soc. of Berlin) 

 were taken in the Brazils, Peru, Buenos Ayres, 

 Chili, Cuba, St. Domingo, and Guiana. At St. Do- 

 mingo, where these insects are abundant, the in- 

 habitants call them Cucuij. They are often applied 

 to useful purposes, as lights, as decorations, and 

 especially to destroy gnats which swarm in the 

 dwellings. Considerable quantities are taken to 

 this effect in the month of June. 



On examining the luminous tissue in Lampy- 

 ris nodiluca, Mater noctilucus, and Elater Ignitus, 

 Macartney observed that this tissue only differed 

 by its yellow colour from the greasy intercellular 

 substance which is found in other portions of the 

 insect's body. In E. noctilucus and E. ignitus 

 the light proceeds from masses 6f this substance 

 elosely applied underneath the transparent parts 

 of the insect's skin. When the season for giving 

 light is passed, this yellow tissue is absorbed and 

 replaced by the ordinary intercellular tissue. In 

 Lampyris noctiluca, besides this greasy tissue, the 

 same author observed, in the last abdominal seg- 

 ment, two small oval sacs formed by an elastic 

 spiral fibre, containing a soft yellow greasy sub- 

 stance of closer texture than that above-mentioned, 

 and affording a more brilliant light than the rest 

 of the luminous tissue.* The light emitted by 

 * Philosophical Transactions, 1810. 



