36 NOMENCLATURE OF~fH CCELUM 



whilst its pair on the other side of the body becomes a pure uroccel : 

 various modifications of this kind are possible. 



8. The coelomoducts belonging to gonoccels may be called 

 " GONODUCTS " (Lankester), whilst the coelomoducts connected with 

 urocoels are to be termed "URODUCTS." Similarly the ccelomo- 

 pores may be called " GONOPORES " and " UROPORES." 



9. When the distinction between ccelomoduct and the rest of 

 the ccelom is marked by the development of a funnel-like mouth, 

 this funnel is termed a " CCELOMOSTOME " (Goodrich). Whilst 

 this is the general term applicable, it will in almost all cases be 

 actually either a "gonostome," i.e. a funnel leading from gonadic 

 ccelom into a gonaduct or a " urostome," that is, a funnel leading 

 from uropoetic ccelom into a uroduct. 



10. The duct-like portion of ccelom ending in ccelomopore may 

 be to a large extent replaced by ectodermal invagination compar- 

 able to the oral ectodermal invagination known as " stomodaeum," 

 and to the anal ectodermal invagination known as "proctodjEum." 

 It is proposed (Goodrich) to term such ectodermal portions of 

 ccelomic ducts " CCELOMOD^EA " (from rb KoiA-w^a, the ccelom, 

 and 68a?oi>, an adjectival form of 6809). The ccelomodsea when 

 existent will, as a rule, be either " GONOD^EA " or " UROD^EA," and 

 it appears that their ectodermal epithelium may, in some cases, 

 acquire renal excretory functions. 



11. Both gonoccels and uroccels with or without specialised 

 gonaducts and uroducts may remain in open continuity with 

 the general ccelom (synccelom), or they may become closed off 

 from it. 



12. The synccelom (general ccelom) may become separated 

 into various chambers with or without obvious or microscopic 

 communication, inter se. It is undesirable to coin special terms 

 for all these chambers, but the possibilities comprise (1) a chamber 

 more especially surrounding, or adjacent to, the main digestive 

 tract, the EPISPLANCHNIC CCELOM; (2) a PERICARDIAL CCELOM; and 



(3) paired EPINEPHRIC CCELOMS. In Vertebrates, the peritoneal, 

 peripleural, and pericardial ccelomic sacs are well known and dis- 

 tinguished besides other minor divisions. These various divisions 

 of the ccelom may communicate or not with one another, or with 

 gonoducts or uroducts, or both. Any or several of them may be 

 obliterated, or may be reduced to a canalicular form. 



13. To be entirely distinguished from ccelomoducts, whether 

 gonoccels or uroccels, are the NEPHRIDIA. Nephridia are probably 

 of ectodermic origin, and in any case arise independently from 

 peculiar superficial nephroblasts or mother-cells. When devoid of 

 internal opening they are called PROTONEPHRIDIA (Hatschek). 



14. Nephridia frequently acquire a funnel-like opening into 

 the ccelom. Such openings are called " nephridiostomes." 



