20 Prof. !M'Intosli's JSolesfrom the 



encysted IMstomes, wliicli might have been introduced by 

 the Rissoce. 



The second species is Nerinides tridentatn, Southern*, from 

 Bhicksud Bay in Lamiunrian roots. Tlie snuut is pointed, 

 with a median ridge which in hiteral view Ibrms two divi- 

 sions — an anterior less elevated and a posterior terminating 

 in the more or less adnate tentacle. In the line between 

 tiie two divisions are the four black eyes arranged in a trans- 

 verse row. The mouth opeus inferiorly, and the extruded 

 proboscis is bcll-sliaped and smooth. The tentacles were 

 absent in the example kindly sent by !Mr. Southern^ Init he 

 describes them as '' short, thick, and lirmly adherent, ot" a 

 deep chocolate colour. ^^ 



The body is nearly an inch in length (16-20 mm.) in life, 

 tapered a little in front and more distinctly diminished 

 posteriorly, -where it terminates in two small rounded lobes, 

 a slight dorsal process indicating the upper edge of the anus. 

 Segments 01-70 short anteriorly, "wider in the middle region. 

 Dorsal surface flattened, ventral rounded. 



The first foot has a small conical papilla or cirrus, and a 

 single (ventral) tuft of translucent bristles with a well- 

 marked curve at the commencement of the tip. If -wings 

 are pi'csent they are very narrow. The second part bears 

 dorsally a small brauchia curved inward, the dorsal lamella 

 being fused to it and ending inferiorly in a truncate edge. 

 A tuft of finely tapered translucent bristles spreads like a 

 fan upward and out-nard. The upper bristles of the tuft are 

 longer and more delicately tapered, and the wings in these 

 are less distinct than in the shorter and thicker forms at the 

 lower edge. The inferior division has a bluntly rounded 

 lamella and a shorter tuft of bristles with traces of wings. 

 At the tenth foot the bianchia is larger, forming a broad, 

 fiat, curved process, the soldered lamella of the superior lobe 

 ending inferiorly in an edge which projects less than the 

 upper margin of the ventral lamella. The dorsal tuft of 

 bristles -has the same structure as in the second, only they 

 are in two rows, are longer and stronger, and the tips 

 less elongated. The lamella of the inferior division has 

 increased in depth, and the bristles are proportionally 

 longer and still stouter than the dorsal. IJoth tufts have 

 a distal curve. Southein dcj-cribes a group of three slender 

 striated setse on the lower margin of the ventral bundle. 



♦ Troc. i{. Irish Acad. vol. xxxi. No. 47, p. 98, i)l. x. fig. 23 a-j. 



