1916 1 Nomland: Invertebrate Zones of Jacalitos and Etehegoin 83 



The beds in which Mya japonica Jay occurs consist of an ashy shale. 

 Gypsum and silicified wood are abundant. The peculiar, so-called 

 bulbous fish growths of many variable shapes form an almost con- 

 tinuous zone here. One of these seemed to be a somewhat water-worn 

 canine tooth. The fauna represents littoral conditions. The indications 

 therefore, seem to be that the Etehegoin sea was growing shallow before 

 passing into the Tulare fresh-water or alluvial beds, as shown by 

 exposures in the Kettleman Hills directly above the Mya zone. The 

 fauna of this zone consists of : 



Glycymeris septentrionalis Mid- Macoma, sp. 



dendorf Mya japonica Jay 



Littorina mariana Arnold Solen sicarius Gould 



Immediately below this, or between the two shale bands, the following 

 forms were found : 



Mulinia densata Conrad Tamiosoma, cf. gregaria Conrad 



Vertebrate Faunal Zones 



As has already been mentioned, a large quantity of fossil leaves and 

 petrified wood is found in the highly colored, perhaps land-laid beds 

 mapped as basal Jacalitos. This collection may, when carefully studied, 

 assist in determining the age of this formation. In these beds fossil 

 remains of the three-toed horse Neoliipparion molle Merriam were 

 found. 



The finding of PUohippus? in the gravels two hundred feet above 

 the basal Jacalitos, or in the bed mapped by Arnold and Anderson as 

 their lowest Jacalitos member, has already been mentioned in this 

 paper. 



Above this no invertebrate or vertebrate fossils have thus far been 

 found until reaching the Glycymeris coalingensis zone, or lowest 

 Etehegoin. The PUohippus stage of the development of the horse is 

 represented here in the basal beds and a few hundred feet upwards. 

 This zone has therefore been called the pliohippus coalingensis zone 

 by Professor Merriam. 



Beginning near the Lower Middle invertebrate zone and extending 

 upward to the uppermost Etehegoin or Mya zone, we have the occur- 

 rence of mastodon, two very different species of camel, a member of 

 the deer family, and a large horse much like Equus or possibly PUo- 

 hippus. The very recent aspect of at least a part of this fauna has 

 cast doubt upon the occurrence of these fossils, and the question has 

 been raised whether these remains may not occur in terrace material. 



