220 L. F. SpatJt — Notes on Ammonites. 



are rather short and stumpy. Some pinkish zoned crystals enclose 

 what appear to be prisms of rutile. The smaller zircons are generally 

 very well rounded. Staurolite is generally seen as small angular 

 pieces, but a few rather larger grains show well-marked striations, 

 probably due to cleavage. Kutile is common, the orange-red variety 

 being the more abundant in rather irregular but often well-rounded 

 grains. Tourmaline is less frequent than usual, chiefly as the olive- 

 green variety ; one large piece is of a curious brick-red colour. The 

 kyanite is quite normal; there are a few large prisms, but most are 

 rather small, and some unusually well rounded. Pale-green pyroxene 

 is rare, and no other transparent minerals were identified. Ilmenite 

 is abundant in tbe usual brilliant black or metallic grains. A pro- 

 longed search did not lead to the detection of either garnet or sphene. 



(To be continued.) 



TV. — Notes on Ammonites. 



By L. F. Spath, B.Sc, F.G.S. 



Y. 



4 S an illustration of the difficulties encountered in basing the 

 XX classification on some peculiarity of the Ammonoid suture-line 

 the case of the two families Macroscaphitinse and Crioceratinse may 

 again be referred to, the former of lytoceratid, the latter of hoplitid 

 origin. Distinction between these two families was based on the 

 bifid or trifid characters of the first lateral lobe. Hamulina nitida, 

 v. Koenen, 1 which shows very nearly equal-sized suture elements, 

 has the trifid first lateral lobe of the type-species of Hamulina, 

 namely H dissimilis, d'Orbigny, but the plain shell of the lytoceratid 

 Anahamulina. Hyatt 2 put the latter into his family Macroscaphitidse, 

 but the former, and also the clearly lytoceratid Pictetia, into Ancylo- 

 ceratidas, i.e. even into a different sub-order. 3 But Anahamulina 

 subeylindrica, d'Orbigny, sp., i.e. the type-species itself, has a nearly 

 trifid first lateral lobe, though it is connected through A. Lorioli, 

 Uhlig, sp. (with a sub-bifid first lateral lobe), with typically lyto- 

 ceratid forms. In ornament and coiling also Hamulina resembles 

 certain lytoceratid forms (compare e.g. the various forms of Macro- 

 scaphitinse figured by Uhlig 4 ). 



Sarasin and Schondelmayer 5 wrote in this connexion: "After 

 having believed, for a moment, that the similarities shown by the 



1 Op. cit., p. 396, pi. lii, figs. 3-5. 



2 In Zittel-Eastman, Textbook of Paleontology, vol. i, pp. 371, 5S8. 



3 The inclusion in Macroscaphitinse again of Hamulina, withdrawal of 

 Anahamulina, the inclusion of Spiroceras in Crioceratinse, and many other 

 alterations introduced by Professor J. P. Smith in the chapter on Ammonoidea 

 in the second edition of Zittel-Eastman's Textbook of Paleontology (1913), 

 and evidently not based on additional research, cannot be considered improve- 

 ments on Hyatt's classification. 



4 " Cephalop.-Pauna d. Wirnsdorfer Schichten " : Denkschr. d. Math.- 

 Naturw. CI. d. k. Akad. d. Wiss., vol. xlvi, Vienna, 1883. 



s "Etude Monogr. d. Ammon. du Cret. Infer, de Chatel-Saint-Denis," 

 pt. ii : Mem. Soc. Pal. Suisse, vol. xxix, p. 154, 1902. 



