Benham. — Notes on Neiv Zealand Polychaeta. 395 



I count 10 and 11 ; the posterior bundles in the smaller are 17 pairs, 

 in the larger 19 pairs. The skin, too, exhibits the same groups of sand- 

 grains. 



From time to time in various parts of the world, even in the European 

 seas, specimens of Sternaspis of larger or smaller size, or with different- 

 coloured shield, &c., have been made into distinct species, but sooner or 

 later, as more careful examination has been made, and as our knowledge 

 of variation and the factors in geographical distribution have progressed, 

 many of these have been absorbed into the type species. So it has been 

 on the American coast, both east and west. It is, indeed, becoming 

 doubtful what are the specific characters of the genus. Even the discovery 

 by Sluiter of a specimen provided with a bifid proboscis {S. spinosa) has led 

 some authors, such as Selenka, to suggest that this feature is present in all 

 species, but that OAving to its fragility and sensitiveness it drops off when 

 the animal is preserved, or even when it dies. 



So far, then, as externals go, it appears that size of body and shield, 

 the colour of the latter, the number of chaetae in the anterior rows and 

 around the margin of the shield, are mere matters of age. For that reason 

 I refer these specimens from New Zealand waters to the type species of the 

 genus. 



What about S. princeps Selenka ? The account* is very brief, but he 

 prefaces it with the words (on p. 5), " It does not seem to be beyond 

 question whether this form . . . can be regarded as really the re- 

 presentative of a new species." Certainly his few lines describing it (on 

 p. 6) do not carry conviction as to its specific separation from S. scutata. 



Only two individuals were obtained, and no measurements are given ; 

 but his figure (of the larger) is said to be three times the natural size, 

 which makes the worm, therefore, 30 mm. in length by 12 mm. in abdominal 

 breadth. As it was " imperfectly preserved," it may be that these 

 dimensions are greater than in life. His account, short as it is, is vague 

 in one or two points. His first sentence — " Along the middle of the ventral 

 surface there runs a shallow furrow " — really applies, as the context shows, 

 not to the body of the worm, but to the shield. Now, this furrow is always 

 present ; it is a line of division between the two halves of the shield. 

 Further, he notes the existence of "an oblique ridge," separating the shield 

 into an anterior larger and a posterior smaller triangular area. This, also, 

 is present in the Naples specimens as in our own. It may be remarked in 

 passing that this feature is not shown in his figure (pi. i, fig. 1). There are 

 "' about 40 bundles " of bristles around the margin of the shield — that 

 is, about 20 on each side. In the larger Naples specimens I find at least 

 19 bundles. So that this is no specific character. 



There is only one other statement : " The whole body is studded with 

 fine scattered chitinous setae, each having at its base a number of smaller 

 chitinous pieces grouped together into wart-like protuberances." If this 

 is really the case, it would be diagnostic of the species. Unfortunately, 

 I have neither Vejdovsky'st nor Kietsch'sf memoirs available here, so that 

 I am unaware whether this histological feature has been described ; but my 

 examination of the skin of the Naples specimens does not support it. Has 

 Selenka confused the sand-grains under a hand-lens ? 



* Selenka, "Challenger" Report, vol. xiii, 1885, Oephyrea. 



t Vejdovsky, Denksch. d. Wien. Akad. Math. Naturw. el., vol. xliii, 1882. 



J Rietsch, Ann. Sci. Nat., 6th ser., Zool., vol. xiii, 1882. 



