174 
THE VOYAGE OF H.M.S. CHALLENGEE. 
splendida (Atlantic Ocean), and Alciopa pacijica (Soutli Sea). Claparede and Panceri, in 
the Annel. Chetop. du Golfe de Naples (1868), gave an account of Alciopina parasitica 
which they found in Cydippe densa; and in his supplemental volume in 1870, the 
former gave further observations on the grouj^, added two new genera, Asterope and 
Vanadis, and used the condition of the snout (cephalic lobe), the presence or absence of 
an appendix to the setigerous lobe of the foot, and the condition of the proboscis (armed 
or unarmed), as a basis for classification. 
An important paper by E. Greeff^ in 1876 gives the best account of the group, both 
historically and anatomically. Like Ehlers he placed them under a special family, the 
Alciopidse, distinguished as follows : — Two large and highly organised reddish eyes, 
and five tentacles. On each side of the foot, ventrally and dorsally, is a brownish 
segmental organ. Foot has a conical setigerous region, with a dorsal and a ventral cirrus, 
flattened into lamellae. The setae are either simple or compound. Body delicate and 
translucent. Pelagic. 
He makes seven genera, the first five of which do not have the head produced in front 
of the eyes. Of these Alciopa has no appendix to the tip of the foot, and the bristles 
are simple. Halodora, like Alciopa, has no armature to the proboscis, nor appendix 
to the foot, but the bristles are compound. Asterop>e has its proboscis lined with small 
hard teeth. It has no appendix to the tip of the foot, and the bristles are compound. 
Vanadis has no armature to the proboscis, one cirriform foot-appendix, and the bristles 
are compound. Greeffia, [Nauphantcd) agrees with the latter in all except that there are 
two cirriform appendices to the foot. The sixth genus Callizona has the head raised into 
a considerable elevation above the eyes. Proboscis without teeth. A cirriform appendix to 
the tip of the foot. Bristles compound. Lastly, Rhynchonerella has also the process beyond 
the eyes, an unarmed proboscis. No cirriform appendix to the foot. Bristles compound. 
Audouin and Milne-Edwards placed the Alciopidse with the Phyllodocidse, and 
the occurrence of large eyes in the remarkable GenetylUs oculata just described is of 
interest in this respect. It is noteworthy that the presence of very large eyes is confined 
to the Phyllodocidse, Syllidse, and Alciopidse, for the organs of such as Nectonereis 
megalops of VerrilH (a Heteronereis-iorm) belong to a different category, though the 
animal swims at the surface of the sea. 
The Alciopidse occur in most oceans — Atlantic, Pacific, Mediterranean, and the China 
Sea. They are very rare in the North Sea. They are met with, moreover, both where 
the surface temperature is low and where it is high, though they appear to be more 
abundant in the warmer seas. 
Very few examples exist in the British Museum. 
1 Nova Acta Acad. Gees. Leap., Bd. xxix.. No. 2, pp. 35-120, Tafn. ii.-vii. 
2 This name is preocenpied, see p. 182. 
2 New England Annelida, pi. v. fig. 1. 
