1903.] NATURAL SCIENCES OF PHILADELPHIA. 725 



they are verj' numerous, each torus of somite XX, for example, con- 

 taining upward of 400, while on XXI, the first abdominal somite, there 

 are but 80. As usual in the genus, they have the form of flat pectinate 

 plates (figs. 12, 13 and 14) set on edge in the integument with the 

 curved teeth exposed, but they are broader apically than in most 

 species and usually have 6 well-developed teeth, the apical one the 

 smallest and occasionally absent, the basal one much the stoutest. 

 the base strongly convex with a prominent posterior process and a 

 small tubercle usually present beneath the lowermost tooth. 



The total length of the type is 107 mm., width in the branchial 

 region 7.5 mm., width at somite XXI 4 mm., number of somites 92, 

 of which 20 are thoracic and 72 abdominal; somites V to XX are 

 setigerous and uncini are present on all somites beginning with V. 



The color when living is olive-green, purest in the posterior region, 

 becoming lighter and more or less tinged with red or yellow anteriorly 

 as a result of the blood-vessels showing through the integument. The 

 tori, particularly on the somites bearing capillary setae, are greenish- 

 yellow edged with a narrow red blood-vessel which forms a red spot 

 dorsad of the fascicles of setae. The ventral plates are yellowish or 

 olive-buff with the prominent anterior border pale green and the 

 furrows and a narrow lateral edging blood-red, while a deep red clot- 

 hke spot covers a narrow area extending over the middle ventral por- 

 tion of somites XII, XIII and XIV, from which a distinct red line 

 marks the course of a subneural vessel to XXI. The lower lip is 

 green, the upper red, the tentacles pale pink. The branchiae have 

 red stalks with green or white branches. 



From most of the nine undoubted species of the genus which have 

 been described from various parts of the world L. viridis is distinguished 

 by its color. From L. turgida Andrews, the only species hitherto 

 taken on the Atlantic coast of the United States, the shape of the uncini 

 and the absence of dark pigmented rings on the tentacles afford the 

 best distinctions. 



The only example of this species known was found by Mr, George 

 Gray burrowing in a soil of sandy mud with A7nphitrite ornata below 

 low water at Ram Island, Wood's Hole, on August 4, 1902. Repeated 

 search since then has failed to bring any additional specimens to light, 

 and as it is a very conspicuous species it must be quite rare or inhabit 

 some locality hitherto unexplored. When brought to me this example 

 occupied a thick mud tube nearly indistinguishable from that of 

 Amphitrite. 



The types of these two species are in the collection of this Academy. 



