452 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Study of Autotomy.* — H. Pieron discusses a number of cases. The 

 autotomy of the elytra of Acholoe astericola, which lives in the ambu- 

 lacral grooves of starfishes, is quite independent of the phosphorescence. 

 There is not usually much autotomy in Blattidas, but it is marked in 

 Blatta (Eetobici) livida as regards all the liinbs. The influence of the 

 position of the exciting stimulus on the autotomy is discussed, and 

 several other problems are raised. 



Dwarf Faunas.! — H. W. Shinier discusses the chief agencies in 

 dwarfing aquatic Invertebrates. He finds evidence of dwarfing as the 

 result of (1) a chemical change in the water (freshening, concentration, 

 increase of H 2 S, etc.) ; (2) the presence of mud and other mechanical 

 impurities in the water ; (3) attachment to floating seaweed ; (4) great 

 changes in temperature ; and (5) great changes in depth. A few examples 

 of dwarfed fossils are given, with a brief discussion of the probable cause 

 of the dwarfing in each case. 



Some abnormality in habitat causes an unusual expenditure of vitality 

 in the continuance of life. There is less energy to spare for growth. 

 Dwarfing would result in forms with comparatively little vitality. Some 

 faunas are composed of relatively small species ; others of small repre- 

 sentatives of species which are larger elsewhere. Dwarfing shows itself 

 in an acquirement of old age characters by the dwarfed animal or by a 

 retention of juvenile characters. 



Rat without a Tail. J — Corsy reports the occurrence of a female 

 rat (Mtis rattus) without any trace of a tail. There was no hint of scar. 

 The sacrum was normal, and behind that there was a coccygeal rudi- 

 ment suggestive of arrest of development. The defect is regarded as 

 congenital. 



Variations in Vertebral Column of Echidna.§ — G. P. Frets has 

 studied a number of skeletons and finds considerable variability. He 

 distinguishes ontogenetic change that seems to spread from behind 

 towards the head, and another which works in the opposite direction. 

 The former is more common and leads to more frequent variations. 



Asymmetry of Skull in Toothed Whales. || — W. Kiikenthal seeks 

 in an ingenious essay to correlate the peculiar shape and movements of 

 the tail-flukes with the asymmetry of the anterior part of the skull. We 

 cannot give his arguments, but the conclusion is that the asymmetry is 

 an adaptation to unequal water-pressure on the front of the head, and 

 this is due to the way the flukes work. 



Early History of Irish Horse. 1 — R. F. Scharff argues that the Irish 

 domesticated Crannog horse is the direct descendant of the apparently 

 wild Shandon horse, and that primitive man domesticated the wild horses 

 which he found in Ireland. He inquires whether the Arab, or, as Prof. 



* C.R. Soc. Biol. Paris, lxvi. (1909) pp. 172-4. 

 t Amer. Nat., xlii. (1908) pp. 472-90. 

 X C.R. Soc. Biol. Paris, lxiv. (1908) p. 987. 

 § Morphol. Jahrb., xxxviii. (1908) pp. 608-53 (14 figs.). 

 || Anat. Anzeig., xxiii. (1908) pp. 609-18 (3 figs.). 

 \ Proc. R. Irish Acad., xxvii. Section B. No. 6 (1909) pp. 81-6. 



