ana fa^^Kiw Formations 73 



shaped groove about 1 mm. long with the shallowing, pointed end towards 

 the aperture, which indicates that the lower end of this ammonite was a 

 close coil, as in Ancycloceras, or a closely apposed limb. These three 

 individuals agree essentially in their sutures. 



DESCRIPTION: Only fragments preserved, showing a small limb, 

 the curve connecting with the larger limb, and a portion of this limb. 

 Suture present ; shell, aperture and lower portion of slender limb absent. 

 The curve, in the type individual does not quite turn to a position parallel 

 to the small limb; and the two limbs are not in contact, at least at the 

 curve. Dorsal side with a central and two lateral flattened smooth strips 

 (the antisiphonal lobe lies on the former), making the cross-section near 

 the turn a very thick crescentic or kidney bean shape, slightly concave 

 dorsally and broadly convex ventrally. The smaller limb is slender in 

 its younger stages and thicker to a point near the curve; here there is a 

 slight dorsal inflation beyond which are no sutures; farther up, at the 

 curve, there is a slight dorsal constriction. The ventral mid-line bears 

 a small ridge which apparently marks the siphuncle. 



SUTURE : The suture is but slightly dissected, and consists of two 



Fig. 3. Hamulina worthensis n. sp., Sutures of type individual, camera lucida drawing, 

 x 16. 



lateral lobes and three saddles, in addition to the siphonal and 1 anti- 

 siphonal lobes. The siphonal lobe is bifid and has two slender elongate 

 tips ; it is about twice as tall as broad. The first and second lateral saddles 

 are nearly equal and similar; each is about half as tall as broad, and is 

 bifid by a shallow, simple lobule. The first lateral lobe is trifid and pro- 

 gressively diminishes in size from the younger to the older sutures. The 

 second lateral lobe is rather smaller than the first, and is bifid. The third 

 lateral saddle is of the same height and about half the width of the other 

 two, and is broadly rounded and unequally bifurcated by an angular notch 



