464 BihJiographical Notices. 



This species has the dentition of Ilerichthys cyanoguttafus ; 

 the latter may be derived horn a type similar to Cichlosoma 

 fenestratum^ with which it agrees in the deep body, strong 

 dorsal spines, interrupted lower lip, insertion of pelvic fins 

 nearly in the vertical from base of pectoral, &c. Tomocichla 

 underwGodi, however, has the elongate body, short dorsal 

 spines, and continuous lower lip o£ G. godmani, with which 

 it also agrees in having the insertion of the pelvic fins far 

 behind the base of the pectoral. 8teindachner's Heros lenti- 

 ginosus may ])rove to be a Tomocichla. 



16. Paraneetroiylus sieholdii, Kner & Steind. 

 Rio Grande de Terraba. 



GoliiidaB. 

 17. P/ii/ypnus maculatus, Giiiith. 

 Kio Ballena. 



BIBLIOGRAPHICAL NOTICES. 



JleredUy. By J. Arthur Thomson. London : John Murray, 

 1908. (Progressive Science Series.) Pp. i-xvi, 1-605. 



Hereditj has always possessed a strange fascination for mankind, 

 though not until recent years has any real grip of the subject been 

 obtained. We have as yet, indeed, done little more than clear a few 

 pathways through the thick undergrowth of tradition and specula- 

 tion which has grown up during centuries of crude experiment and 

 rule-of-tlnxmb practice. 



The work so far accomplished, however, is sufficient to show that 

 the riddle of heredity is one of the most difficult which the biologist 

 has yet attempted to solve. Analyze and experiment as we will, 

 that intangible property of puUulation peculiar to living matter still 

 remains one of Nature's secrets. Whether it will ever be wrested 

 from her time alone will prove, but the attempt is being made, and 

 in earnest. Already an appalling amount of literature on the 

 subject has come into being, not all of which is worthy of the 

 theme. Prof. Thomson, however, set himself the task of sifting 

 and systematizing this output, and that he has been singularly 

 successful in wiunowing the chaff from the grain is beyond 

 dispute. The results of his labours are now presented to the v/orld 

 in a volume which will be regarded as the standard work of refer- 

 ence to this subject for some years to come. To the biologist it 



