1 86 DR. F. E. BEDDARD ON THE 



likeness shown by the vertical, radiating and lateral tubes to 

 the canal-system of a Ctenophore, while recalling the views of 

 Lang, Willey, and others as to the Ctenophoran affinities of the 

 Platyhelminths; I illustrate this by the accompanying text-figure 

 (text-fig. 6). 



I have verified other facts in the anatomy of this genus which 

 have been dealt with by Diamare and Cohn, but have not found 

 it necessary to treat of- them at length. Inasmuch as both 

 Fnhrmann * and Ransom f query certain characters in their 

 definitions of the genus Amabilia, I have thought it worth 

 while to append a fuller definition, derived from my own first- 

 hand knowledge of the Oestode, which is of course confirmatory 

 in great part of Diamare and Cohn, but which contains some 

 fresh characters described in the present paper. I do not dis- 

 tinguish between family and generic characters as I do not think 

 that the systematic position of T atria is yet fully settled. I am 

 unable, of course, to differentiate between generic and specific 

 definitions since but one species is known. 



Genus Amabilia Diamare. 



Scolex very small ; rostellum armed with a chitinous ring ; 

 suckers four, unarmed. Proglottids with a lateral ridge on each 

 side, not of great length, continuous dor sally and ventrally. 

 Longitudinal muscle-layers disposed in two and occasionally 

 three rows of bundles ; modified in their arrangement in fully 

 mature proglottids. Water-vascular system consists of a median 

 stem opening by a pore both dor sally and 'centrally, of two transverse 

 vessels on each side connecting this with two lateral longitudinal 

 vessels, one lying above the other ; these communicate at the orifice 

 of the transverse vessels; there is no network of small tubes. 

 Testes one or two horizontal rows, four to six deep, disposed in two 

 groups separated by ovary, rarely forming a continuous row. 

 Cirrus-sac large and muscular, two in each proglottid, opening on 

 each side of body between lateral water-vessels and dorsal to nerve- 

 cord ; cirrus armed with numerous spinules J. Vas deferens short, 

 without coil, opening into an oval vesicida seminalis connected by a 

 short duct with cirrus-sac. Ovary single, consisting of fine fila- 

 mentous threads radiating out from base where oviduct arises. 

 Vagina opens into an anteriorly placed diverticulum of vertical 

 ivater '-vascular tube. Uterus consists of a dorsal and a ventral 

 netxoork connected by vertical tubes. Rip>e eggs long and spindle- 

 shaped §. 



* Zool. Jahrb. Suppl.-Bd. x. 1908, p. 88. 



t Bull. U.S. Nat. Mus. No. 69, 1909, p. 103. 



£ When the cirrus-sac is protruded in ripe segments it is accompanied by the 

 intervening cortical la3 r er which forms a sheath. 

 : § Fide Liihe I have not been able to observe ripe. eggs. 



