analogy points to the fact that geological epochs separate the Rhinoceros "Auklet" 

 from the Guillemots and the Murrelets and the Auklets proper, which some authori- 

 ties would tumble together into a single sub-family. We have in the Alciformes the 

 prettiest example of the evidential and definitive value of the egg — an example which 

 is as unimpeachable as it is significant. 



Relying, then, upon the uncontradicted oological evidence, we distinguish five 

 families of the Alciformes; and inasmuch as we are relying upon the egg characters 

 alone, we take the liberty to make them diagnostic for each family, leaving to the 

 anatomist the task of reconciling his conclusions, or of taking issue according to 

 his appraisal of the evidence. 



The critical material upon which this diagnosis is based comprises representa- 

 tions of nineteen species and two subspecies of the Alciformes in the cabinets of the 

 Museum of Comparative Oology. Ten species, viz., Ptychoramphus aleuticus, Brachy- 

 ramphus hypoleucus, Synthliboramphus antiquus, Cepphus columba, Uria troile califor- 

 nica, Uria lomvia arra, Alca torda, Lunda cirrhata, Fratercula arctica arctica, and Cer- 

 orhinca monocerata, are represented in considerable series. This material is supple- 

 mented by the definitive plates of seven eggs of Alca (Plautus) impennis, appearing in 

 Ootheca Wolleyana (Vol. II, Plates XIV-XXI, pp. 364-384); and the excellent illus- 

 trations of the eggs (one each) or iEthia pygmaea, Brachyramphus marmoratus, 

 Brachyramphus brevirostris and Fratercula arctica naumanni, in Bent's recent mono- 



Eggs of Lunda cirrhata Eggs of Cerorhinca monocerata 



A general comparison of the eggs of the Tufted and Horn-billed Puffins 

 Case XVII, 34, Annex Case XVII, 33, Annex 



graph (Life Histories of North American Diving Birds, U. S. N. M. Bulletin 107, 1919). 

 All that lacks, then, of completeness in this apparatus, is eggs of Cepphus (Pseuduria) 

 snowi, Brachyramphus perdix, and Synthliboramphus wumizusume, and these, all be- 

 longing to well-known genera, may be presumed to conform to the established types. 



Order ALCIFORMES. 



Family iEthiidae, Auklets. 



Subfamily -ffithiinae: Egg: Shape: ovate or short ovate, rarely oval, but usually 

 with little end well rounded. Color: pure white, or pale bluish white, without trace of 

 previous or "reminiscent" pigmentation. Texture: closely matted or slightly granular, 

 without luster. Number: singular. 



Ptychoramphus aleuticus (Pallas), Cassin's Auklet. 



Phaleris psittacula (Pallas), Paroquet Auklet 



iEthia cristatella (Pallas), Crested Auklet. 



.ffithia pygmaea (Gmelin), Whiskered Auklet. 



iEthia pusilla (Pallas), Least Auklet. 



Comment: The eggs of this group are quite uniform in appearance, fairly con- 

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