Athorncophoniti.\ GASTROPODA. 7!l'.t 



the median groove in front, and the papillae are of lighter colour ; there 

 are in most specimens irregularly distributed small black spots above 

 and below the perinotum ; sole uniformly light yellow. Head trans- 

 versely oval, separated from the sole by a deep groove ; oral lobes 

 very distinct, oval, separated by a narrow flat ridge, and limited on 

 the inner and outer side by distinct frontal grooves. Tentacles re- 

 tracted. Head-shield extending to about half-way between head and 

 mantle, with a median groove, which is shallower than the side 

 grooves. The notum is thickly covered with very prominent round 

 papilla 1 , arranged in longitudinal rows, 5 in a lateral field behind the 

 mantle, but gradually reduced from 4 to 2 in front of the mantle. 

 The median groove extends nearly the whole length of the back, bifur- 

 cating on reaching the tail-tip. Lateral grooves narrow, slanting back- 

 wards, very seldom bifurcating towards the margin, and extending, 

 through contraction in alcohol, over hyponotum and sole ; there are 

 about 18 to 21 grooves on each side, 9 of which are post-pallial. A 

 distinct preanal groove is present. The mantle is distinctly triangular, 

 limited by grooves ; at the anterior angle and in the median groove is 

 the renal orifice, covered by a small oval flap ; the pulmonary orifice 

 subcentral. The anal opening is on the right side below the mantle, 

 but nearer to the perinotum. The hyponotum is very distinct, 2 mm. 

 broad ; the perinotum is also well marked, nodulous, no doubt through 

 contraction in alcohol. Sole aulacopod, again the result of contrac- 

 tion. The shell is rudimentary, consisting of about 20 small white 

 calcareous grains of various shape and size, the largest having about 

 1 mm. major diameter. 



Measurements of largest specimen : Length over back from head 

 to tip of tail, 28mm. Width of back to perinotum, 16mm. Sole- 

 Length, 25 mm. ; breadth, 7 mm. Breadth of hyponotum, 2 mm. 

 Anal orifice llmm. behind the right tentacle and 2mm. above the 

 perinotum. Pulmonary opening 14 mm. behind the right tentacle. 

 Genital orifice 011 right side of the right tentacle. 



Jaw as usual in the genus, the median basal projection sharply 

 produced, but sometimes worn off. 



Radula with numerous teeth, the central tooth small and slender, 

 with 3 small cusps and a blunt denticle on each. Lateral teeth with 

 about 7 denticles, the 2 innermost largest. 



Pedal gland long, nearly half the length of the sole, narrow, flat, 

 thin. 



Reproductive Organs. The sheath of the male organ is rather 

 long, convolute, narrowed toward the distal end, where the vas deferens 

 enters and the retractor muscle is fixed ; the verge armed with papillae. 

 There is a short vagina, with the receptaculum seminis near its proximal 

 end. Albumen-gland large, oval, yellowish. The hermaphrodite gland 

 is globular, large, light brown ; the hermaphrodite duct not very 

 long and convolute. No accessory glands. 



