162 Prof. M'lntosh'd Notes from tU 



conserved the genus Sp'io without definitely defining it, and 

 described under the name >^p\o filicerms, O. Fabr., a species 

 which he (Mesnil) has deruonsi rated to be very near his 

 Spio martinerisis, and he doubts if Malragren's form is that 

 of Fabricius, though tiie figure pertains to the same genus. 

 He docs not accept Levinsen's inclusion of the ge lus Nerine 

 of Johnston under Spio. He does not, in short, know any 

 species falling within the description of the two species of 

 Fabricius as entered by O. F. Miiller. 



For the present purposes the genus Spio may be charac- 

 terised, after Me<nil, as having a prostomium witliout 

 frontal tentacles ; branchiae from the first setigerous segment 

 to the end; anus surrounded by cirri ; always two rows of 

 bristles in each division ; and after a certain segment (Hth 

 to 15th) the posterior row is formed by winged hooks. The 

 first species is Spio Jilicornis, O. Fabr., which has a snout 

 somewhat like that of Pobjdora on a large scale, or akin to 

 that of P</^05/>io, with a blunt bifid raed an rostrum and a 

 bulging process of the buccal segment on each side. Two 

 or three minute eyes occur on each side of the median ridge 

 posteriorly. The median process passes from the tip of the 

 snout backward to end in a conical papilla. The body is 

 2-3 inches in leng;!), broad and scaicely tapered iu front, 

 but gradually diminishing to the moderately slender jjosterior 

 end, which has two thicker cirri dorsally and two more 

 slender cirri ventrally. The segments range from GO to 80. 

 The ligulate branchiae occur on all the bristled segments. 

 The superior lamella of the 10th foot is bluntly rounded 

 dorsally and slopes obliquely to the wide notch inferiorly. 

 The ventral lamella is more or less semicircular. The bristles 

 of the upper division form a wide tuft ; the longest superiorly, 

 and all are curved backward and wingetl. The ventral 

 bristles are somewhat shorter, but similarly tapered, and 

 some of the lower forms present a slight dilatation in the 

 winged region. The type of bristle rapidly changes, for at 

 the 14th foot, or sooner, a row of hooks appears in the ventral 

 series, with finely tapered short bristles in front, and a lew 

 winged bristles inferiorly. The upper lamella gradually 

 diminishes, and still more the inferior, so that the setigerous 

 process becomes prominent, and a group of bristles at the 

 ventral edge of the inferior division becomes modified — 

 each being curved, flattened, and furnished with a hook or a 

 probe-tip. The winged hooks have straight shafts, which 

 increase in bulk superiorly, then curve backward and slightly 

 dilate before the contraction at the throat. The strong and 



