indicated by an epithelial lining that is continuous with and 

 similar to the outer epithehum. 



Female accessory organs Organs in the female beside the ovary 

 and eggs; in the acoels these consist of the seminal bursa and 

 associated parts, but may be lacking altogether. 



Female germinal center Area where the earliest stages of devel- 

 opment of eggs are found; in the acoels it is not delimited by 

 a capsule and is continuous with the string of eggs which 

 move along the body as they develop; "ovary" is often used 

 to include both the germinal center and the string of eggs. 



Flagellar organ Organ consisting of several flagella in an 

 elongated channel at the anterior end of the body in some 

 members of the order Nemertodermatida. The flagella arise in 

 an oval enlargement at the proximal end of the channel and 

 may be protruded through the open end of the channel at 

 the anterior tip of the body. 



Frontal gland Group of gland cells whose ducts open at the 

 anterior end of the body either singly or variously combined, 

 with or without a small ampule at the outer end of the ducts. 



Germinal center See "female germinal center," "male germi- 

 nal center." 



Haptocilia Specialized cilia with adhesive tips. 



K'Ornerkolben cells Large club-shaped gland cells with coarse 

 secretory granules; characteristic of the intestine of the 

 Nemertodermatida. 



Male antrum Passage leading to the male organs which is 

 considered to be an inpocketing of the outer body wall as 

 indicated by an epithelial lining which is continuous with 

 and similar to the outer epithelium. 



Male copulatory complex All organs involved in the transfer 

 of sperm to a partner. This includes the penis and associated 

 glands and ducts. 



Male germinal center Area where the earliest stages of sperm 

 development take place; not set off by a wall or capsule and 

 may be scattered groups of cells; "testes" often used for 

 this general area. 



Nozzle See "bursal nozzle." 



Outer body wall Includes the outer epithelial layer and the 

 underlying circular, longitudinal, and, if present, oblique 

 muscle layers plus intermingled parenchyma and gland 

 cells. 



Ovary Includes the female germinal center and the string of 

 developing eggs; see "female germinal center." 



Parenchyma The mass of generalized cells filling most of the 

 body in acoels; peripheral parenchyma is the outer part of this 

 mass which surrounds the body organs; the central paren- 

 chyma is the more vacuolated central part in which digestion 



occurrs. 

 Penis Glandular, muscular, or cuticularized structure which 



serves directly to convey sperm to the partner; a wide variety 

 of structures are included under this term. 

 Penis sac Sac, not part of the wall of the penis, that surrounds 

 the penis and may also surround the seminal vesicle and, in a 

 few cases, the male antrum also. 

 Peripheral parenchyma See "parenchyma." 

 Pharynx simplex A simple tube that structurally is an inturned 



part of the outer body wall. 

 Prostatoid organ A thick-walled pocket containing a secretion 

 and, sometimes, with a cuticularized point or needle at its 

 open end; may open either into the male antrum or onto the 

 ventral surface of the body; believed to function as a 

 stimulatory ("reizorgan") or adhesive organ; compare 

 "adenodactyl." 

 Rhabdites Oval to elongate-oval rods, secreted by, and lying 

 in, outer epithelium or in epithelial cells sunken into the 

 parenchyma; may be clear, semitransparent, or colored and 

 may protrude on the surface of the body. 

 Rhammites Similar to rhabdites but long, sinous, or irregular 

 in shape and always found in cells sunken into the paren- 

 chyma. 

 Seminal bursa Walled sac that receives and stores sperm from 



a partner. 

 Seminal vesicle Area where sperm accumulate before ejacula- 

 tion; a true seminal vesicle is a walled organ associated with 

 the male copulatory organ; a false seminal vesicle is simply a 

 space in the parenchyma associated with the copulatory 

 organ or the male genital pore. 

 Spermatic duct Duct leading from the seminal bursa; may 

 be outside of the bursa (bursal appendage) or may be in- 

 verted inside the bursa; may be cuticularized (bursal nozzle) 

 or may consist only of cellular and /or muscular elements; 

 may act as a sphincter. Its evolutionary precursor appears to 

 be only a cap of cells (see Dorjes 1968a:73-74). 

 Statocyst Sense organ in anterior end of body. In Acoela it is 

 composed of a cellular vesicle which contains a lithocyte 

 enclosing a statolith; in Nemertodermatida it is similar but 

 contains two lithocytes, each with a statolith. 

 Syncytial bursa Area in the parenchyma where bundles of 

 sperm received from a partner accumulate and which thus 

 serves as a bursa in addition to or in the place of a seminal 

 bursa. 

 Testis See "male germinal center." 

 True seminal vesicle See "seminal vesicle." 

 Vagina Passage leading to the seminal bursa whose lining 

 epithelium and wall structure does not correspond to that of a 

 female antrum, or where a passage is present in addition to 

 the female antrum; this term is loosely used and not well 

 defined. 



