reticulorumen

…However, in primitive mouse deer species, there is no third stomach and there are three chambers. In the narrow sense, the second stomach is considered to be the anterior end of the first stomach and is treated as one pouch, and is often called the rumen reticulorumen (first and second stomachs). The rumen (narrow sense) is a large pouch that occupies most of the abdominal cavity, about 80% of the total stomach volume, and in cattle it is 100 to 150 liters. …

*Some of the terminology explanations that mention "reticulorumen" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…ただし原始的なマメジカ類では第三胃がなく3室である。狭義には第二胃を第一胃の前端部と考えて一つの囊として取り扱い，反芻胃reticulorumen(第一･二胃)と呼ぶことが多い。反芻胃(狭義)は腹腔の大半を占め，全胃容積の80％内外，ウシで100～150lもある大囊である。…

※「reticulorumen」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報