OPHELIIDAE. 383 



The blood is reddish from the presence of haemoglobin. It contains a 

 number of rounded and in part, at least, amoeboid corpuscles, which are colored 

 with haemoglobin from the surrounding medium. The fluid gives its color to 

 the brancliiae and commonly to the body in general. 



There is a short, evaginable proboscis, often forming a simple button, with 

 rosette-like folds. Intestine commonly filled with sand or other material from 

 the medium in which they live. 



The opheliids live in large part in pure sand, but often occiu- in sand mixed 

 with mud, or in mud or slime sometimes of a strongly odoriferous character. 

 They burrow in the sand and mud like lancelets. WTiile they are essentially 

 shallow water forms, some occasionally are found at considerable depths; and 

 Kesun fusus, the interesting form described below (p. 38G) was secured at the 

 great dei)th of 2,463 fathoms and Travisia 'profundi at 2,222 fathoms, depths 

 much exceeding any other recoided for the family. 



The resemblance to Amphioxus in habits of many species is accompanied 

 by a corresponding superficial resemblance in form, as well as in size, trans- 

 lucency, consistency, movements, and distribution, as pointed out by Willey 

 (Ceylon pearl oyster fisheries report, 1905, pt. 4, p. 288) in his note on Armandia 

 lanceolata: "Although infinitely removed from each other in morphology, 

 Armandia and Amphioxus ai'e closely approximated in bionomics. It is a case 

 of true homoplasy; there is no question of affinity, nor of mimicry, nor of paral- 

 lel evolution." These resemblances were previously pointed out by Lo Bianco 

 (Atti R. acad. sci. fis. nat. Napoli, 1893, ser. 2, 5, no. 11) for another species of 

 the same genus, Armandia polyopthalma. Some forms are very sluggish, such as 

 Ophelia limacina and, in general, other species of this genus and also the species 

 of Travisia. In captivity these forms exhibit merely slight elongations and 

 contractions, or roll about rather inertly, sometimes thrusting the snout here 

 and there. The strong muscular development, however, indicates considerable 

 power in bm-rowing. On the other hand, as pointed out by PhiUippson (Zool. 

 anz., 1899, 22, p. 417), Polyopthalmus is specialized for locomotion, and the 

 contrast it affords with the preceding highly sedentary type, he thinks, clearly 

 exhibits the artificiality of the much used division of the polychaetes into the 

 Sedentaria and Errantia. Also very active is Ammotrypane, Mcintosh (British 

 annelids, 1915, 3, pt. 1, p. 17, 21) remarking in regard to A. aulogaster: "The' 

 extraordinary activity and vigor of the hving animals at once attract attention. 

 They exceed most armelids in the display of violent muscular action, as they 

 rush about in every direction through water or sand, mucus or mud, and then 



