REPORT OF THE DIRECTOR I916 12$ 



7 The claim which was made by Henn regarding the relicts, that, 

 they are small and inconspicuous forms, is also applicable to the 

 persistent types of geologic history. The immortal forms are 

 throughout of the most lowly organisms, as the Foraminifera; the 

 brachiopods of the Lingula and Crania types ; gastropods of the 

 Capulus and Patella types ; small pelecypods as Leda, Lucina, 

 Nucula and Modiola. 1 



ally vigorous types which, at the summit of their vigor, extended downward 

 to depths which were physically the same as the great abysses of today ; and 

 thus the deep-water types of one area reappear as shallow-water types of 

 another into which competing forms have never intruded, and types found 

 from the littoral to great depths in one part of the world are confined to great 

 depths in another." 



There is no isolation in the air as there is on islands, in the rivers or in 

 subterranean life. Hence we find hardly any persistent types and relicts 

 among the insects and birds. 



A group of ancient types has found isolation in a nocturnal habit. Austin 

 H. Clark (op. cit, p. 19), in discussing the "types of faunal restriction," 

 has pointed out this fact as follows : 



" The strictly nocturnal habit, nozv known to be a characteristic of a num- 

 ber of fishes and other organisms once supposed to be confined exclusively to 

 the deep sea, and long appreciated in regard to a number of diverse terrestrial 

 groups, is an attribute of ancient types, or of types which have not been able 

 to maintain themselves under normal conditions, and is therefore comparable 

 to a habitat in the deep sea or in any other biologically unfavorable situation." 

 As typical relicts among the mammals of nocturnal habits we may cite the 

 Proximii or lemuroids of Madagascar and India, among them the lori 

 (Stenops) and Kobold maki (Tarsius spectrum) which has large spectacle- 

 like eyes, and our opossum. 



1 The number of examples among the vertebrate relicts is immense ; among 

 the most striking are the insectivores, notably the shrews ; the monotremes, 

 marsupials, Xenarthrae (armadillos, ant-eater, sloths) with their gigantic 

 ancestors in South America; the Kiwi (Apteryx) of New Zealand, as the 

 last survivor of the gigantic Mioas ; the small reptiles as the survivals of the 

 Mesozoic giants. Animals of immense proportions are in all classes a post- 

 climacteric phenomenon ; gigantism indicates already the decline and approach- 

 ing extinction of the race. Such animals lack a compensatory element in the 

 environment, which fact leads to their destruction. The gigantic reptiles, the 

 Dinosaurs, the gigantic crocodiles, snakes, all became extinct, but the small 

 representatives of these orders survive. The mammals are now furnishing 

 the giants in the whales and pachyderms, but it is doubtful whether mammals 

 larger than man will survive. Tt is obvious to every one that the small forms, 

 as the mice and shrews, hold their own better under all conditions than the 

 larger types, just as the small mammals did in the Mesozoic age against the 

 gigantic reptiles. 



Likewise the lizards (Lacertilia) which are throughout small as compared 

 with the extinct reptiles, are one of the latest and most flourishing side 

 branches of the reptiles and not until now reach their climax. Among the 

 amphibians the partly gigantic Stegocephali have become extinct in Paleozoic 

 and early Mesozoic time, while the pisrmaean salamanders and frogs and bur- 

 rowing small Caecilia are very well able to hold their own against the higher 

 reptiles, birds and mammals. 



Special notice in this connection is deserved by the remarkable Phanero- 

 branchia with exterior gills (represented by the Axolotl, Siren, Proteus, 

 Menobranchus) and the Cryptobranchia with "gill-apertures" (Amphiuma, 

 Menopoma. Cryptobranchus). These remarkable relicts are persistent 

 ontogenetic stages of the salamanders, as is especially shown by the Axolotl 

 (Sircdon) which under certain circumstances may change into a salamandroid 

 form. It is also interesting to note the asylums these strange relicts have 



