120 EXPLANATION OF PLATES. 



Fig. 2. Small piece of branchial sac, to show spicules. S. }. 

 Fig. 3. Dorsal tubercle of adult B. pachydermatina. S. 1. 

 Fig. 4. Dorsal tubercle of B. </ibbosa, Heller. S. 1. 



PLATE CYN. II. 



Fig. 1. Boltenia tubcrcnlata, Herdm., nat. size. 



Fig. 2. Branchial and a trial apertures of another specimen, showing 



many lobes. 

 Fig. 3. Branchial aperture of a specimen, showing four chief lobes and 



many smaller. 

 Fig. 4. Specimen removed from test and cut open to show folds of 



branchial sac, compound tentacles, dorsal tubercle, &c., 



slightly enlarged. 

 Fig. 5. Small part of the branchial sac from the inside, to show 



spicules. S. ^. 



Fig. G. Boltenia tubcrcnlata adhering to Xti/cla llliitclcggii, n. sp. 

 Fig. 7. Four specimens of Bolic.nia tuberculata, nat. size, along with 



two specimens of Styela Whitel&ggii, n. sp., nat. size. 



PLATE CYN. III. 



Fig. 1. Microcosmus DrascJtii, Herdm., from the left side, about half nat. 



size. 

 Fig. 2. Diagram of longitudinal section through the animal to show the 



relation in size between the test and contained body, reduced. 

 Fig. 3. The body removed from the test, from left side, nat. size. 

 Fig. 4. Section through the test near the apertures, to show the irregular 



outer surface, nat. size. 

 Fig. 5. Part of the mantle, highly magnified, to show the arrangement 



and appearance of the calcareous spicules. 



PLATE CYN. IV. 



Fig. 1. Specimen of Microcosmus Draschii attached to a large Ascidia 

 phallnaiolftcs, and having one specimen of Polycarpa Sl/iitc.ri 

 (P 1 -) and three specimens of 3Iolt/ttl<t Forbcsi, Herdm., (P 2 -) 

 attached to its surface, nat. size. 



Fig. 2. Microcosm UK DinscJiii cut open to show the folds of the branchial 

 sac, the opening of the oesophagus, the dorsal languets, the 

 tentacles, and the dorsal tubercle. 



Fig. 3. Part of the back of the branchial sac to show the longitudinal 

 and transverse rows formed bv the spicules, 



" 4- ' 



