Parker. — (hi an " Index- ( ullection." 75 



From this it seems to follow that the best way to arrange a 

 small index-collection of the kind mentioned in the preceding 

 paragraph, is in the form of a solid phylogenetic diagram or 

 " genealogical tree."" 



The model now exhibited is an attempt to carry out the 

 principles just laid down. In it the main line of descent from 

 protozoa to the higher vertebrata is represented by a vertical rod 

 of wood three feet high, about 1^ inches in diameter at its lower 

 end, tapering somewhat towards its upper end, and firmly fixed 

 below into a flat stand about one foot square. The various 

 groups which do not lie on this main line are represented by 

 side branches, which have usually an upward direction, but are 

 inclined downwards from their point of origin in the case of 

 degenerate types. Actual specimens, or, when these are un- 

 attainable, models of one or more examples of each group are 

 placed in appropriate positions on the stem and branches, and 

 labels are attached, giving (a) the name of the group, (b) the 

 name of the representative specimen or specimens, and (c) the 

 place in the Museum where the collection of specimens of the 

 group is to be found. 



I need hardly say that in the present condition of our know- 

 ledge of zoology, the subjective element enters very largely into 

 the construction of a model such as this, and that the progress 

 of research is certain to make alterations in detail necessary. I 

 hope, however, that T have succeeded in representing with some 

 degree of accuracy the mutual relations of the various animal 

 groups. 



Near the bottom of the stem is placed a model of an Amceba 

 (A. radiosa), representing the myxopodous or pseudopod-bearing 

 section of the protozoa, and a little higher up a model of one of 

 the collared monads, (Monosiga gracilis) representing the masti- 

 gopodous or ciliuni-b earing section of the same group. Close 

 to the monad arises an ascending side-branch, bearing on its 

 extremity a specimen of one of the New Zealand fibrous sponges 

 (ChaliniiJa sp.) as an example of the Porifera. 



A short distance above the Amoeba and the monad, on the 

 main stem, the group of Coelenterata is supposed to begin, and is 

 represented by models of a jelly-fish (Chrysaora cyclonota), and 

 of a sea-anemone (Stomphia churcliiw), the former being sus- 

 pended by a wire, the latter placed on a small bracket. From 

 this part of the stem a branch arises, representing the echino- 

 derm phylum, and bearing a specimen of a star-fish (Asterias 

 forhesii). 



Still higher up the main stem the Type or Sub-kingdom Vermes 



*My friend Professor Haddon, of the Boyal College of Science, Dublin, 

 has devised a most ingenious form of " diagram in three dimensions," excel- 

 lent for lecture purposes, but less suitable in many ways for permanent 

 exhibition in a museum than the one I propose. 



