W. A. HKRDMAN. 



ri,ATI-; VI. 



-Lf/>tiirliniiin i/hiiitilr, from a photograph ; X -. 

 -Coarsely ^rauiilar fells from ihc test ; X t". 



Stcllatf spii'iiles, fnuii the test ; X 40. 



-Surface of an Astitlio/.ooiil, showinjr branchial aivrture iiiul distribution of spicules. 

 -StrreodnveUa antanliai, larger colony. 



„ „ smaller colony. 



-.\nterior part of an A.scidiozooid. 

 -Anuirowitim (intantiium, from a photograph. 

 -Section of the colony. 



Part of u section of the colony showing Ascidiozooids. 

 -,\scidioz()oid extracted from test. 



Anterior cud of Ascidiozooid enlarged. 

 -Part of branchial sac. 

 -Sli/ela rolidiila, from a photograph. 

 -Part of branchial sac. 



Part of surface of test, showing scales ; X 40. 



.Mimentary canal. 



:\Iantle : X 40. 



Dorsjil tubercle. 



PLATE VI f. 



Fif;. 1. — Bnllniia arotti ; natural size. 



Fig. 2. — .\trial aperture of same. 



Fig. '^. — Another specimen with shorter stalk. 



Fig. 4. — Atrial aperture of same magnified to show spines. 



Fig. T). — Smallest specimen of same. 



Fi(!. G. — Atrial aperture in profile to show spines. 



Fi(i. 7. — Surface of test, magnified, showing three spines. 



Fig. 8. — Two test spines in profile. 



Fig. 9.— Dorsal tubercle of specimen shown in lig. 1. 



Fio. 10. — Part of branchial sac and dorsal lamina'of specimen shown in fig. 1. 



Fig. 11. — Test in section, showing spines on surface. 



Fio. 12.— Unidentified Cynthiid (see p. s). 



Fig. 13.— One of the 4-lobed apertures of same. 



Fig. 14. -Oiknplpiira fluiissiai, Lohm., about natural size. 



Fig. ITi. — Tip of tail of same enlarged. 



Fig. k;. — A, II, c, and n. — Four sections through the tail of 0. gaiisxira to show different degrees of 



develoi)ment of muscle bands above and below the notochord. 



Fig. 17. -Magnified details of the wall of notochord, the muscle layer, etc., to show histological 



structure. 



