74 Mr. F. E. Beddarcl on a 



c is the apodenie beliind the 1st maxilla ; f) and c together 

 form the area of subsidence described in the text which gives 

 rise to the great fold commencing the endophragmal system of 

 Astacvs anteriorly. 

 Fi(/. 3. Tlie same, four sections further in towards the median plane. 

 Fi(/. 4. The same, three sections further in than 3. 



d and /, apodemes between m" and the 1st trunk-limb, 

 and between the 1st and 2ud trunk-limbs. li\ Astacus f \\»,ii 

 been drawn to the position marked/', as shown in: — 

 Fi;/. 5. The same, five sections fui'ther in than 4. 



7'V//. 6. Seven sections further in than 5. The gnathobases are seen as 

 distinct appendages ; the anterior trunk apodemes are no longer 

 visible, only the large one, behind the underlip, which forms the 

 support of the sternal plate and the anterior attachment for the 

 longitudinal musculature, remains. In the specimen these 

 mnscles had been torn from the apodeme, as shown in the 

 drawings. The apodemes which are still visible in the poste- 

 rior segments are clearly seen to have travelled backward 

 so as to come nearly over the segmental constrictions poste- 

 rior to those to which they properly belong. This gives us 

 the posterior branch of the endopleurite oi Astacus {ef. text). 

 ' c, eggs in the genital tube. 

 Fif/. 7. A nearly median section. 



n, tiie ventral cord thrown into slight waves by the ventral 

 constrictions. 



m, teeth of the mandibles. 

 oc, the oesophagus. 

 vu/, the wall of midgut. 



.s^^, the median portion of the sternal plate which binds the 

 two apodemes behind the underlip across the middle line. 

 Tlie underlip is represented by the ridge I. It is to be noticed 

 that no muscles run into the nnderlip excepting here, close to 

 the median plane. These bands may have originally formed 

 the true anterior ends of the ventral longitudinal muscles. 



IX. — On a neio Genus of Oh'goc]iceta,coviprising Five new 

 Species, helonging to the Family Ocneroclrilidaj. By Frank 

 E, Beddard", M.A., F.R.S., Prosector to the Zoological 

 Society of London. 



[Plates VI. & YIL] 



Contents. 



I. Introductory, p. 74. 

 II. Description of five new Si)ecies of Gordiodrilus, p. 7o. 



III. Diagnoses of Genus and Species, p. 93, 



IV. Alfiuities of the Genus Gordiodrilus, p. 96. 

 Y. Explanation of Plates, p. 97. 



I. Introductory. 

 The material upon which the present paper is based con- 

 sisted of a large number of living worms, all of which I 

 received, through the kindness of the Dire ctor of the Royal 



