Appendix 263 



the Challenger. The hydroid, subsequently named Monocaulus 

 imperator, is described by Professor Allman ; see his Report on 

 the Hydroids, Part ii, page 5 and Plate 3 (Challenger Reports, 

 Zoology, vol. xxiii.). It had a stem more than 7 ieet long and was 

 brought up from a depth of 2900 fathoms, off Yokohama, in lat. 

 34 37' N., long. 140 32' E. 



My thanks are due to not a few friends, too numerous for separate 

 mention, for their help in difficulties arising from incorrectly written 

 words in the Minute Books or from my own ignorance, but especially 

 to Professor H. G. Plimmer for his care in transmitting to me those 

 Books, and above all others to Professor \V. W. Watts, Sc.D., F.R.S., 

 my old friend and former pupil, who has read all the proofs of 

 Section II. and has detected several misprints and other errors which 

 had escaped my notice. Such errors insist on creeping into books, 

 and this is not likely to be an exception, for I have hardly ever 

 read a new one without detecting two or three misprints. But 

 I fear there may be others. As the communications made to the 

 Philosophical Club range over a wide field of knowledge, it is occasion- 

 ally possible that a statement may not be accurately reported, and 

 if the author of it were absent from the reading of the Minutes, this 

 may have passed unnoticed. Some such cases I have observed and 

 corrected, but others, in subjects with which I am unfamiliar, 

 have no doubt passed undetected. In other cases, to one or two 

 of which I have called attention, the speaker has been wrongly 

 informed. Lastly, the ' somebody who blundered ' may have 

 been myself. After a certain time in life we become too well aware 

 that accuracy does not increase with years. So for mistakes of 

 my own making I crave the reader's pardon and ask him to 

 remember Horace's genial dictum : " Scimus, et hanc veniam petimus- 

 que damusque vicissim." 



