268 DR. A. E. TRUE MAX OX THE [vol. lxxiv, 



while the venter is well rounded and does not show the low arch 

 of Liparoceras. 



It is more difficult to separate L. sparsicosta from certain species 

 of Beanicercts. Mr. Buckman proposed this latter genus to include 

 A. luriduni (1, vol. ii, p. Hi) placing it with the Liparoceratidie, 

 but its affinities are with the Dactvloids rather than with the 

 Liparoceratids (see p. 292). Beanicercts hiridum is a capricoin 

 form, probably a catagenetic descendant of a tuberculate cadicone 

 (that is, a form with the whorl thickest at the ventral margin) ; 

 such cadicones of the Beanicercts series have been detected at 

 Napton and elsewhere, and with them also occur ammonites which 

 resemble B. luridum, and have strongly-ornamented cadicone inner 

 whorls, the outer whorl having normal Capricorn ornament, in some 

 cases very similar to that of L. sparsicosta. The young of such a 

 form is figured in PI. XXIII, tig. 2, the shape of the whorl being 

 very different from that of the young of Liparoceras sparsicosta 

 (PI. XXI, fig. 3 ft). The chief points of distinction of these series 

 are : 



(1) The stronger ornament of the inner whorls of Eexniceras ; the capr'- 



corns of the Beaniceras series are catagenetic, those of the Liparc- 

 ceratidae are anagenetic. 



(2) The steep central part of the umbilicus of Bean'ciras (due to the 



cadicone inner whorls). 



(3) The suture of Beaniceras frequently shows a A -shaped median cell, 



as was pointed out by Mr. S. S. Buckman (1, vol. ii, No. 73). 



This last-named character, however, is not constant ; it is not 

 alwaj^s present in Beaniceras, and may sometimes be seen in other 

 capricorns. The arrangement of the sutural elements is somewhat 

 similar in Liparoceras and Beaniceras : in Napton specimens of 

 the latter the first lateral lobe is relatively wider. In development, 

 the sutures of Beanicercts are more complicated than the sutures of 

 Liparoceras at similar diameters. Thus the suture of Beet ni cere s 

 at 5 mm. (text-fig. 8 b, p. 236) is quite as advanced as that of 

 L. sparsicosta at 15 mm. 



Liparoceras hexerouexes (Young & Bird). (Pig. 4<°, p. 270.) 1 



Refigured, Androgynoceras heterogenes (Young & Bird), S. S. Buckman 

 (1, vol. i, No. 46). 



Iletains Capricorn form up to a diameter of 00 mm., the last whorl 

 being swollen ; bituberculation commences earlier than in L. sparsi- 

 costa, certainly before a diameter of 20 mm. If L. heterogenes is 

 properly assigned to the Liparoceras series it is probably a little 

 more advanced than L. sparsicosla. 



This species was formerly referred to the genus Androgynoceras, 

 but it appears to belong to Liparoceras, since it shows whorl height 



1 The sutures shown in figs. 4 (a, e, /), 7, 8 (a, b), 10 (b, c), and 13 were 

 drawn from the left-hand side of the specimens, but are here reversed for 

 convenience in comparing them with others. 



