630 



MOLLUSCA 



PHYLUM VI 



Acjoniatites Meek (Ajjhyllites Mojs.) (Fig. 1173); Palaeogoniatites Hyatt. Type 

 P. (Goniatites) lituam (Barrande). Devonian. 



Paraphtjllites Hyatt. Type P. (Goniatites) tabuloides (Barr.). Dorsum of this 

 involute form is entirely occupied by a large azygous lobe terminating in a minute 

 annular lobe and partial cone similar to that observed in Nautiloids and in Pinacites. 

 The inner extension or cone is not present elsewhere among Ammonoids so far as 

 known. Devonian. 



Pinacites Mojs. Highly involute, compressed ammoniticones with acute venters. 

 Septa biconcave, owing to a division of the lateral lobes by narrow saddles which 

 are conncctefl by ridges with corresponding saddles on the dorsum. There are also 

 saddles at the umbilical angles and on either side of the ventral 

 lobes. The azygoiis dorsal lobe is large. Dorsum with one pair 

 of narrow zygous saddles and one pair of broad zygous lobes, 

 giving a formula of eight lobes and eight saddles. European 

 Devonian. 



Family 4. Tornoceratidae Giirich. 



Involute forms, with ventral sinus, simple septa like those of 

 Fig. U7-4. ^^'^^ Apkyllitidae, and relatively short body-chambers. 



Tornoceras simplex (v. Tomoceras Hyatt (Fig. 1174), Maeneceras Hyatt (Fig. 1176). 



Buch). Upper Devonian; i-. . J \ b /> J \ a / 



Budesiieim, Eifei. Devonian. 



Family 5. Cheiloceratidae Freeh. 

 Ammoniticones varying from discoidal and Anarcestes-like to highly involute, com- 



FiG. 1175. 



Suture-line of Sjioradoceras 

 miinsteri (v. Buch). 



Fig. 1176. 



Suture-line of Manneceras 

 tcrehratus (vSandb.). 



Fig. 1177. 



Suture - line of Agnnidcs 

 xulcutns (Miin.ster). Upper 

 Devonian ; Fichtelgebirge. 



Fig. 117S. 



Aganides rotatorius (de Koninck). Lower Carboniferous ; 

 Tournay, Belgium. 



pressed shells with narrow venters. Shells smooth, but with frequent labial constrictions. 

 Body chamber long. Aperture without hyponomic sinus. 



In this family the septa are concave along the mesal plane as in Nautiloids, 

 becoming convex only internally and laterally, following the broad internal saddles in 

 the zone of involution. Lobes and saddles entire. Primitive forms may have only 



