400 THE LIAS AMMONITES. 



Ammonite from the Marlstone Rock Bed at Gretton, near Winchcombe, and at 

 Dumbleton and Alderton, Gloucestershire ; South Petherton, Somerset ; near Charmouth, 

 Dorset ; associated with Lytoceras fimbriatus, where I have found them in the same block 

 of rock. Professor Judd has collected numerous specimens of large size and great beauty 

 in the Middle Lias Clays of Ouston, Billesdon, Roscart, Rutlandshire. In Yorkshire it is 

 collected at Hawsker, Staithes, RockclifF, Hummersea, HuntclifF, and Saltburn, from 

 coast sections of the Marlstone Beds. 



In Prance it has been collected from the Upper Beds of the Middle Lias in all the 

 departments in which strata belonging to the Amal. margaritatus zone occur. 



In Germany, in Alsace, near Uhrweiler, it is found in all its varieties in blue clay, 

 beautifully preserved with its calcareous shell ; at Metz, near the banks of the Moselle, 

 imbedded in blue clay in great numbers. It is found in Swabia in many localities, and is 

 widely distributed through the Middle Lias of Wiirtemberg ; it is found at Wasseral- 

 fingen, Kirchheini, Metzingen, Sondelfingen, Breitenbach, Hinterweiffer, Hechingen, 

 .Prommern, Aselfingen, and at Wutach, according to Oppel, and in numerous localities 

 throughout North Germany according to Brauns. 



Amalthecs EngelhardtIj d Orhigny. PI. LXX. 



.\mmonites Engelhardti, (TOrhigny. Paleontol. Fran9aise ; Terr. Jurass., i, pi. 66, 



p. 245, 1842. 



Diagnosis. — Shell discoidal, compressed; whorls compressed; sides flat and longi- 

 tudinally costated ; costge consist of elevated ridges of shell closely approximated with 

 longitudinal narrow valleys between the ridges ; external costse more closely approxi- 

 mated ; siphonal area narrow, sharp, and cutting ; aperture oblongo-lanceolate. 



Dimensions : English specimen. — Transverse diameter 205 milhrn^tres ; width of 

 umbilicus 30 millimetres; height of aperture 110 millimetres. 



Fretich type specimen. — Transverse diameter 250 millimetres, in relation to the 

 diameter width of the last whorl -^§q ; amount of involution -^§-5 ; thickness of the last 

 whorl Y^o ; width of umbilicus ^|^. 



Description. — The shell of this interesting Ammcmite is much compressed, subcarinated, 

 and ornamented on the sides with small longitudinal costse, not much elevated, and more 

 closely approximated on the outer half of the shell. When the shell, which is extremely 

 thin, is preserved the longitudinal costge are crossed by very fine transverse striae result- 

 ing from the growth of the shell, and giving a highly ornate appearance to the sides of 

 the whorl. The extreme tenuity of the shell renders the opportunity rare for inspecting. 



