204 INDEX. 



Porto Santo, origin of the name of, 49 ; a generic area of radiation 

 for certain Helices, 130. 



Predacious insects, less numerous in the tropics, 28, 29. 



Prostemma guttula, Fabr., the development of the wings of, 100, 101 . 



Psylliodes, a variable species of, in Lundy Island, 60. 



erythrocephala, Linn., two distinct states of, frequently indi- 

 cated, 105. 



marcida, Illig., pallid hue of, 64. 



nigricollis, Mshm, a pale state of the P. erythrocephala, 105. 



vehemens, "Woll., varies from isolation, 90. 



Pterostichus, its various divisions are natural ones, 175. 



Ptini, their stature affected by isolation, 74 ; which characters of, 

 are the most constant, 104. 



Ptinus albopictus, Woll., its changes on the islands of the Madeiran 

 Group, 75 77- 



Pupa, often two distinct states of, 106. 



Purpurarice of the ancients, probably the Madeiran Group, 141. 



Pyrenean region, the, perhaps a primary area of diffusion, 130. 



Reasoning, not sufficient of itself for the formation of science, 159. 



Red-Admiral Butterfly, its introduction into Madeira perhaps re- 

 cent, 74. 



Reduviadce, on the development of the wings of a representative of 

 the, 101. 



Representative species, exemplified by the Madeiran Helices, 128, 

 129, 185; where frequently to be recognized, 183. 



Rhyzopertha pusilla, Fabr., unaffected by climate, 31. 



Rivers, their power of transporting insects along their course, 149. 



Saline spots, variation of insects in, 57. 



Salvages, occurrence of a Canarian form on the, 120, 124. 



Saprinus, a modification of Hister proper, 143. 



- nitidulus, Fabr., two distinct states of, indicated, 106. 

 Scarabceus, the capture of, out at sea, 150. 

 Scarites abbreviatas, Koll., large size of, on one of the Madeira 



Islands, 88 ; varies both from isolation and altitude, 91. 

 Sciences, the, should assist rather than oppose each other, 155, 156. 

 Scydmcenus Helferi, Schaum, smaller in Madeira than in Sicily, 65. 

 Scymnus, an apterous species of, in Porto Santo, 82. 

 Sea, inconstancy of insects in the vicinity of the, 57. 

 Sicily, the fauna of, has much in common with that of Madeira, 139. 

 Silpha atrata, Linn., presents a distinct state in Ireland, 33. 

 Silybum Marianum, Grtn., its stalks the food of a Ptinus, 76. 

 Similitudes, Lord Bacon on the importance of, 13. 

 Sitonia gressoria, Illig., perhaps a form of the S. grisea, 33. 

 Sitophilus granarius, Linn., unaffected by climate, 31. 



