NO. 1 HARTMAN : POLYCHAETOUS ANNELIDS 43 



gate, distally flaring pieces, fused for a short distance along their median 

 line near the anterior end, and sometimes more or less calcified distally. 

 The maxillae are often also thin, translucent, or only slightly chitinized ; 

 the carriers are usually broad, short, basally rounded or somewhat pointed, 

 lacking a median unpaired piece. Forceps (maxillae I) are broad, falcige- 

 rous, without dentations at the base; maxillae II to IV on the left side are 

 usually multidentate, and maxilla V on either side is either a single 

 smaller tooth or a simple plate; on the right side maxillary plates III 

 and IV are fused (such that maxilla IV appears to be absent). The 

 dental formula within any one species is believed to be too variable to be 

 of specific significance or, conversely, too consistently alike between 

 species to be significant in the differentiation of species. Since these parts 

 are relatively weakly developed, it appears that the onuphids are not the 

 rapacious predators that some other members of the Eunicea are. 



Tubes, on the whole, are very characteristic of species; they usually 

 consist of a thinner or thicker parchmentlike base (translucent in Hyali- 

 noecia), smooth within, on the outside of which are attached foreign 

 particles of various sorts. In some there may be only a thin layer with 

 a coat of fine sand particles (Nothria iridescens Johnson), or the sand 

 may be partially replaced by similar, larger particles, including gravel, 

 shell fragments, debris, etc. Tubes may be very slender, nearly filamen- 

 tous, long, stiff, resembling those of some phoronids, externally covered 

 with fine gravel (Onuphis nebulosa Moore). They may be proportion- 

 ately much broader in diameter, covered externally with coarse particles, 

 bits of shells and sticks, presenting a very untidy appearance (Diopatra 

 ornata Moore), or the tube may present a neatly annulated appearance 

 (Diopatra tridentata n. sp.) in which there are inner and outer parch- 

 mentlike layers, between which fine sand and mud particles are placed. 

 The form or structure of the tubes is nearly as great as the numbers of 

 species constructing them. However, it would be unsafe to base any 

 determination on the tube alone, since it has been found that similar 

 tubes are constructed by species in widely related groups, or that the 

 same species may use different building materials, depending on what is 

 available. 



On the whole, the Onuphidae are difllicult to determine specifically 

 without a careful examination of internal and external microscopic parts. 

 Superficial gross structures, such as distribution and kind of branchiae, 

 proportions of parapodial lobes, proportionate lengths of prostomial parts, 

 are of generic use but are too uniform within genera to have any specific 

 significance. Then, too, collections often include individuals largely in- 



