90 RECORDS OF THE AUSTRALIAN MUSEUM. 



*DENDROTROCHUS, Pilsbry, ASSIGNED TO 

 TROCHOMORPHA. 



By C. Hedley, F.L.S. 

 [Plate XXI.] 



From considerations of shell characters, and perhaps of geogra- 

 phical distribution, Pilsbry attached f to the genus Papuina, a 

 compact and newly defined group, Dendrotrochus, embracing the 

 species kindred to (Helix) helicinoides, Hombron and Jacquinot. 

 The author of it added that the soft anatomy of the section was 

 unknown to him. 



Some examples of the animal of the type species collected by 

 Dr. V. Gaunsou Thorp, of H.M.S. "Penguin," presented by him 

 to Dr. J. C. Cox, and transferred by the latter to the Australian 

 Museum, have just been examined by myself. The I'esult is to 

 convince me that at least T. helicinoides, and probably the species 

 Pilsbry associates with it, must be dismissed from the genus 

 Papuina, and be ranked under the genus Trochomorpha. Those 

 features in which Dendrotrochus leans from Trochomorpha towards 

 more normal Zonitidse, namely the tripartite sole, caudal mucous 

 pore and side cusps of the rachidian tooth, induce me to hold it 

 as closer than Trochomorpha proper to a primitive stock. The 

 evidence furnished by the foot, dentition and genitalia of Den- 

 drotrochus harmonise, in the classification I propose, with those 

 characters of its shell which are emphasied in the diagnosis of the 

 section. On page 1 of the work above cited, " columellar margin 

 arcuate, short, not dilated or reflexed," is italicised as an important 

 distinction of Trochomorpha; while on page 143, "columellar lip 

 not expanded or reflexed " is given similar prominence in the 

 description of Dendrotrochus. 



It is a matter of regret to the writer that his inquiries should 

 have led him to mar with corrections a single page of so brilliant 

 a work as Pilsbry's " Guide to the Study of Helices ;" but the 

 progress of knowledge thus exacts its dues as we rise, to para- 

 phrase the poet, on stepping-stones of our dead classifications to 

 higher things. 



* Since this article was in print, I have received a letter from Mr. 

 Pilsbry, discussing this classification. Accepting the proposed reform, 

 he points out to me that Stoliczka described (Journ. Asiat. Soc. Bengal, 

 xlii., Pt. ii., p. 20) a rudimentary tail pore in Sivella. From my des- 

 cription he now considers " that Dendrotrochus is an arl)oreal section or 

 subgenus of Trochomorpha retaining an old character in the tail pore." 



fMan. Conch. (2) ix., p. 143. 



