148 BULLETIN OF THE BUREAU OF FISHERIES. 



19. Ancula pacifica MacFarland. 



Ancula pacyica MacFarland, op. clt., p. 53. 



Body slightly compressed, smooth, limacifonn, liitrhcst in front of the Ijranfhifc, tapering posteri- 

 orly to the tip of the long pointed tail, anteri. .i ly >1. .jiiii'.' hss rapidly to the high rounded head (pi. xxx, 

 fig. 23). General color clear, translucent yc-ll..\\ ish w hitr, a narrow median line of orange on dorsum 

 extending from between tlie rhinophores td thr liranrhiir, and continued behind the branchial plumes 

 along a S'lii.'lit ( iv-l In thi- tip ..f the tail, ('i)on each side along the indistinct dorso-lateral margin a 

 similar (iran-.- lin'- i\tiii'liii- I'nim the rhinophores to the extrabranchial appendages, continued 

 between thnr Kasi- and |irMl(inj,'cd for a very short distance behind the last one. 



Head (pi. xx, fig. S9) bluntly rounded, no frontal veil, the tentacles short, slender, bluut, and 

 slightly flattened. 



Rhinophores nonretractile, large, the clavus perfoliate, with 9 yellowish leaves, which are oblique 

 behind and horizontal in front. The stalk of the rhinophores as long as the clavus, cylindro-conical, 

 its base with two long finger-like processes nearly as long as the whole rhinophore, directed obliquely 

 forward and outward, tipped with orange. The distal end of the rhinophore projects beyond the 

 clavus as a slightly enlarged truncate C3'linder (pi. xxx, fig. 2.3). 



Branchial plumes 3, nearly equal in sine, bipinnate, in part tripinnate, nonretractile within 

 sheaths, a single median anterior plume and a lateral one on each side, the main subdivisions tipped 

 with orange. Immediately behind the bases of the plumes and free from them is the small cylindrical 

 anal papilla, the renal pore situated near its base on the right side and in front. Borne on the dorso- 

 lateral margin on each side of the branchial plumes are 4 blunt, club-ahaped processes, dilated above, 

 contracted at the base, the upper third of each light yellow, tipped with orange. In one individual 

 the number of these extrabranchial appendages was reduced to 3 on each side. 



Foot narrow, the .sides nearly parallel, tapering posteriorly to the tip of the slender tail, the ante- 

 rior end abruptly rounded. 



Dimensions of the largest individual taken: Length 16 mm., breadth 2 mm., height 3.5 mm. 



Pharyngeal tube very short, pharyngeal ))ulb small, 1.5 mm. long by 1.5 mm. high, inclusive of 

 crop, and 1 mm. broad, the sucking crop spherical, prominent, connate. 



Labial disk convex, nearly circular, armed with a strong spinous armature, the "prehensile col- 

 lar" of Alder and Hancock, broadest below (0.1.50 mm.), narrowing laterally and incomplete above. 

 The elements of the armature (pi. xx, fig. 90) are light yellow in color and arranged radially with 3-6 

 plates in each row in the lower part. The fundamental shape of these elements is the same, a broad 

 <'urved base with posterior bifid extremity, in front rounded, the upper surface arched and gradually 

 rising into a blunt hook direitted outward. The innermost teeth have strongly curved bases, the outer 

 ones less so, the outermost teeth smallest. Toward the upper part of the ring the teeth become very 

 small, are reduced to the innermost row and have the hook directed sharply outward (pi. xx, fig. 91); 

 the larger ones below are less oblique. The distal end of the hook is minutely serrulate, the denticles 

 thus formed being much smaller and more numerous than in ^L criatata (4-5, Bergh ) . The largest plate." 

 of the labial armature measure about 0.252 mm. in length, the tip of the hook 0.012-0.015 mm. wide. 



Eadula narrow, colorless, the teeth in 35 rows increasing in size markedly from front to back of 

 radula, the most posterior teeth being twice the size of the most anterior ones. 



Rhachis narrow, bearing a single quadrangular median plate, slightly broader behind than in 

 front (pi. XX, fig. 92) and occasionally giving indications of being made up by the fusion of a pair of 

 plates in the median line. In the first 8-10 rows of the radula these median plates are absent, but 

 are constant in the remaining portion. They are not produced artificially by the breaking off of th. 

 basal ])ortion of the first pleura} as indicated by Bergh for A. cristaia (1880, 1. c). Length of avera." 

 median plate 0.018 mm., its width 0.012 mm. 



The pleural teeth are 2 in number, the first one large, with an irregular transver,se base and a 

 concave, triangular vertical body placed slightly oblique to the median line of the radula. The inner 

 margin is thickened, bears 11-17 recurved sharp denticles, and terminates above in a strong hook 

 ( pi. XXI, fig. 93 ) . The height of a first pleural tooth from the middle region of the radula is 0.084 mm. 



The second [ileural teetli are triangular, thicker below, thin above, terminating in a strong apical 

 hook. 



