PLATE XXVIII. 
Figs. 1-4. Aplidium fallax, Johnston. 
Figs. 5-7. Aplidium leucophcBum, n. sp. 
Figs. 8-10. Aplidium fuscum, n. sp. 
Figs. 11-13. Aplidium despectum, n. sp. 
Figs. 14, 15. (?) ignotus, n. sp. 
at. Atrial aperture. 
at. 1. Atrial languet. 
hr. Branchial aperture. 
en. Endostyle. 
h. m. Horizontal membrane of branchial 
sac. 
i. Intestine. 
1. Languet. 
1. V. Fine longitudinal vessels of bran- 
chial sac. 
p.ah. Post-abdomen. 
r. Eectum. 
sg. Stigmata of branchial sac. 
sg'. Small stigmata. 
st. Stomach. 
t.c. Test cells. 
t.m. Test matrix. 
tr. Transverse vessels of branchial sac. 
Fig. 1 . Two colonies of ’ natural size. 
Fig. 2. Ascidiozooid of Aplidium fallax, seen from left side ; magnified (S., 1 inch). 
Fig. 3. Part of branchial sac of Aplidium fallax, showing diminution of stigmata 
{sg, sg') at ventral edge ; magnified (S., 1 inch). 
Fig. 4. Dorsal part of branchial sac of Aplidium fallax, showing languets ; magnified 
(S., 1 inch). 
Fig. 5. Colony of Aplidium leucoplmum; natural size. 
Fig. 6. Ascidiozooid of Aplidium leucophceum, seen from left side ; magnified (S., 1 inch). 
Fig. 7. Dorsal part of branchial sac of Aplidium leucophcmm, showing stigmata and 
languets; magnified (S., 1 inch). 
Fig. 8. Colony of Aplidium fuscum ; natural size. 
Fig. 9. Part of branchial sac of Aplidium fuscum ; magnified (S., 1 inch)'. 
Fig. 10. Anterior end of Ascidiozooid of Aplidium fuscum, showing branchial and atrial 
apertures; magnified (S., 1 inch). 
Fig. 11. Colony of Aplidium despectum; natural size. 
Fig. 12. Section of test of Aplidium despectum; highly magnified (S., ^ inch). 
Fig. 13. Part of branchial sac of Aplidium despectum; highly magnified (S., ^ inch). 
Fig. 14. Colony of (?) ignotus; reduced (see measurements); 
Fig. 15. Part of colony of (?) ignotus; natural size. 
