﻿Plate 38 



Phascolosoma agassizii Keferstein 



Figures of hooks for comparison, continued from plate 37: 



IG, 17, Humboldt Bay; same specimen as figure 15; 0.063 X 0.052 and 0.066 



X 0.05. 

 18; Humboldt Baj'; from one of the darkest brown specimens; 0.063 X 0.05. 

 19, 20 Crescent City, from same specimen; 0.059 X 0.059 and 0.052 X 0.056. 

 21, 22 Friday Harbor, Wash.; 0.077 X 0.08 and 0.063 X 0.063, different speci- 

 mens. 



23, Ucluclet, British Columbia; 0.07 X 0.07. 



24, Huston Inlet, Queen Charlotte Islands; 0.073 X 0.073. 



25, Sitka, Alaska; 0.073 X 0.07. 



26, Kodiak, Alaska; 0.042 X 0.049. 



27, 28 Cape Fox, Alaska, same specimen; 0.052 X 0.0595 and 0.056 X 0.05. 

 29, 30 Monterey Bay, vicinity of Point Pinos, from j'oung specimen 20 mm. 



long, introvert extended, 0.038 X 0.031. Figure 30 is X 400 and 29, 



another hook, X 800. 

 31, Humboldt Bay, Calif. Modified papillae from preanal region of a large 

 dark brown female specimen, X 20; at lower right a papilla in profile. 

 The papillae are bent away from introvert. 



Plate 39 



1, Phascolosoma agassizii Keferstein, Humboldt Bay, Calif.; X 2. A specimen 



in which the fixing muscle has been strongly contracted so that the rectum 

 is lengthened. C, coecum; F, fixing muscle; F', its esophageal branch; 

 A^C, nerve cord; RV, left ventral retractor; S, anterior end of spindle 

 muscle; W, wing muscles, 1, 2, S, et cetera, muscle bands to right and 

 left of nerve cord. 



2, Phascolosoma nigrescens Keferstein, Albatross station 4160, Hawaiian Islands; 



a hook 0.07 X 0.08 mm., X 400, for comparison with Ph. puntarenae; 

 , a, the thickening or fold in the basal plate characteristic of nigrescens. 



3, Phascolosoma puntarenae Grube; tentacular crown, X 8; nuchal organ in 



middle. 



4, Phascolosoma dentigerum (Selenka and de Man), San Carlos Bay, Baja Cali- 



fornia; X 30. Tubercles from dorsal surface of a contracted specimen, a 

 short distance in front of anus which is below middle of figure. 



5, Phascolosoma dentigerum; X 2. Specimen from El Pulmo Reef, Baja Cali- 



fornia, to show areas of enlarged tubercular papillae. A, anus. 



6, 7 Phascolosoma dentigerum. Two hooks, 0.056 X 0.063 and 0.056 X 0.05 



mm.; X 4C0. 



8, P'lascolosoma antillarum., Grube and Oersted, an egg; X 100. 



9, Phascolosoma antillarum; X 3. Dorsal aspect of anterior portion of speci- 



men from Espiritu Santo Island, showing tentacular crown, the heart- 

 shaped nuchal organ in center, second collar, introvert, and anal region 

 (darker). An introvert papilla shown enlarged. 



450 



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