New Polychaetous Annelids From Laguna Beach, California
RALPH V. CHAMBERLIN
In a very interesting collection of annelids from Laguna Beach transmitted to me for study by Prof. Hilton, the apparently previously undescribed forms listed below are represented. As a comprehensive report on the annelids of the region to follow further explorations and collecting is in contemplation, I am giving here only such preliminary accounts of the new forms as are thought sufficient for their identification in the local fauna. The types of all these species are in the Museum of Comparative Zoology at Cambridge.
POLYNOIDAE
Halosydna latior sp. nov.
A species proportionately broader over all than the usual forms of the common H. insignis, californica, and pulchra. It is characterized by elytra not only closely imbricated along each side but also broadly overlapping in the middle line throughout the length. The elytra in general are unusually elongate in an oblique direction, the long axis running from the outer end cephalomesad; the outline subelliptic, the caudomesal edge broadly convex, the opposite one a little incurved at middle. The entire surface of elytra subdensely covered with very small rounded brown nodules or tubercles; within the middle region, just behind the edge of the preceding overlapping elytron, a number of much larger paler tubercles which in the type are present on all excepting the last pair. Elytra extending to outer ends of parapodia. Eighteen pairs of elytra present. Prostomium subangularly bulging on each side, the anterior eye at the angle, the posterior eye removed far caudad, by about half the greatest width of the prostomium. Paired anterior prolongations of the prostomium very long, as long as the median length of the prostomium back to level of posterior eyes, distally clavate. Median ceratophore much stouter than the lateral prolongations and exceeding them by more than a third in length. Median tentacle long, nearly attaining end of palpi; slender, narrowing distad, only slightly thickened subapically, with the usual slender tip which is of moderate length. Lateral tentacles much shorter, their tips reaching only to near middle of light region between proximal black region and subapical black ring of median tentacle. Tentacular cirri resembling median tentacle in form, being narrowed distad with subapical enlargement slight; one or two fine setae emerging from a small nodule at distal end of parapodium proximad of tentacular cirrus. The notocirri in general have the same characteristic form as the tentacular cirri, narrowing continuously distad with the subapical enlargement slight. First neurocirrus very elongate, surpassing the parapodium. The other neurocirri slenderly cylindroconical, narrowed into a slender tip and a little narrowed proximally; attached well toward base of parapodium the end of which they fail much of attaining. A characteristic feature is the elongate form of the nephridial papillæ, these in the type as preserved being mostly near three times as long as thick at the middle. Neuropodial setae dark amber colored, numerous, arranged in two continuous regions, a narrow dorsal one and a much broader ventral one in the latter of which the setae form four distinct longitudinal series with five or six setae in each series. Notopodials moderate in number, the dorsal ones short, the most ventral long, attaining the end of the neuropodium. The elytra are greyish with dusky or brownish mottlings. Notocirri with dark annulations as usual.
Length, 42 mm.; width to end of setae, 14 mm.; to end of parapodia, 10.8 mm.; exclusive of parapodia, 7 mm.
Taken on Laguna Beach at Mussel Point (Hamilton coll.).
Type—M. C. Z. 2, 138.