THE 



YOYAGIE OF H.M.S. CHALLENGEK. 



ZOOLOGY. 



REPORT on the Monaxonida collected by H.M.S. Challenger during the 

 Years 1873-76. By Stuart O. Ridley, M.A., F.L.S., late Assistant 

 in the Zoological Department of the British Museum, and Arthur 

 Dendy, B.Sc., F.L.S., Associate of the Owens College, and Assistant 

 in the Zoological Department of the British Museum. 



PREFACE. 



In presenting this Eeport it seems desirable to give some explanation with regard to 

 the arrangement of the work. We have always felt strongly the great importance of 

 minute anatomical and histological investigation in describing sponges. Owing, however, 

 partly to the unfavourable condition for histological purposes of a large proportion of the 

 material at our disposal and partly to the limited space of time available for the 

 completion of the work, it has been found impossible to work out the minute anatomy 

 and histology of all the species in the collection. Hence we have found it advisable to 

 investigate in detail some of the leading types only, and to confine our remarks on the 

 subject to a special chapter in the Introduction, making them at the same time rather of a 

 general nature. 



We have to express our sincere thanks to Mr. John Murray, the Editor of the 

 Challenger Reports, in the first place for placing so valuable and interesting a 

 collection in our hands, and in the second place for the great indulgence which he has 

 shown us while preparing the Report. We have also especially to thank Professor 

 Flower, F.R.S., Director of the Natural History Department of the British Museum, and 



(ZOOL. CHALL. EXP. — PART LIX — 1887.) NuD « 



