284 SOMK KKSILTS OF OSTRICH INVESTIGATIONS. 



iiig intermediate degrees, as a result of crossing, 

 we should still have the knowledge that their distinctive nature 

 could be extracted by selective breeding. When discussing inter- 

 mediate forms, the possibility of segregation should always be 

 borne in mind. Among the African fauna especially, experimental 

 breeding would proljably establish that many so-called species and 

 sub-species, often f(_)unded upon one or a tew specimens, are in 

 reality intermediates or hybrids of other species. 



So long as we have the facts before us, it is of small moment 

 whether we regard the northern and southern ostriches as distinct 

 species or not. It becomes a matter of individual prediliction 

 whether greater importance should be given to somatic differences 

 or to physiological similarity. Without being biassed in either 

 direction, it appears to the writer to make for convenience to 

 regard them as distinct under the names bestowed by Linnaeus and 

 riurnev. 



DESCRIPTJOXS OF PLATES AND TF.XT FIGURES. 



Pl. 2.\. — Group (if North .\frican Ostriclics. 



Pl. 2b. — Group of Soutli African Ostricht-s in full plumage. 



Pl. 2C. — Troop of first generation (1'") cros.s-lired ostriches at the 

 Grootfontein School of Agriculture. 



Pl. 3.^. — Plume showing " bars " and defective growth ])elo'\v, result of 

 malnutrition. 



Pl. 315. — Pair of tirst generation ( ¥2) cross-bred ostrich chicks. 



Pl. 4.\. — Egg of North African (left) and Soutii African (right) 

 ostrich. 



Pl. 4B. — Outer surface of fore-wing of ostrich, v/ith plumes cut off, the 

 quills showing the arrangement of the feathers in rows. 



Pl. s.\. — Inner surface of fore-wing of ostrich, with plumes cut off, 

 showing the naked surface, incomplete row of under-coverts and 

 outline of the tliird digit. 



Pl. 51!. — Part of inner surface of wing, showing the projecting third 

 finger, witii an irregularity in the row of under-coverts and wing- 

 cjuills at the same place. 



Fic. I. — Diagrammatic representation of stage at which plumes 

 are clipped to avoid injury to bird. Clipping takes place along 

 the line a, b, tlie pith, or medull;i, having receded below; clipping 

 along the lint c. d. wouUl expose the medulla and result in 

 hemorrhage. 



I"i<;. 2. — Head of North \frican Ostrich showing baldness. The 

 clear, oval area towards the hind part of the bald patch represents 

 the pineal spot. 



Fig. 3. — Tarsi and feet of Northern ostrich. The scutellation 

 shows a strong break between the tarsus and the large, inner, third 

 toe, and the beginning of a second break over the middle_ joint 

 of tlie toe. The small, outer, fourth toe bears only a few scales, and 

 the claw shown is unusually well-developed. 



Fig. 4. — l'pi)cr surface of head of ostrich chick, showing the 

 ]>ineal spot. 



