THE CRINOIDEA 



193 



cc r- 



muscular articulation, and to IBr 2 by incomplete syzygy. Arms hetero- 



tomous ; each gives off 5 unbranching rami nearly as stout as the main 



stem, 2 to right and 3 



to left, or vice versa; the 



first main -axil is the 



10th or llth brachial, 



succeeding branches are 



at much greater inter- 



vals ; pinnules occur 



below lAx, on IBr 4 6 8 



Amb 



or IBr 



those 



/Br_. 



being as a rule epizy- 

 gals. There are dis- 

 tinct Amb and adAmb, 

 both in arms and teg- 

 men. The proximal 

 region of the arms is 

 fixed by the tegmen, 

 so that the grooves of 

 the proximal pinnules 

 rise from the tegminal 

 food - groove (Fig. 

 XXIV.). Small iBr 



1, 1J f -on Tegmen of Calamocrimis Diomedat, with the arms and pin- 



rest on snoulders OI UK niiles cut oft" down to the level at whicli they become fixed in 



and iner^e into imper- *^ e calvx - Amb, ambulacrals or covering-plates ; As, anus ; 



. ax, axial canal of arm ; cc, coeliac canal of arm ; fg, food-groove 



torate iAmb, and these of anterior arm where it joins the tegminal food-groove ; IBr, 



na<5 infn -nnr-ifuTv-ma primibrach ; iAmb, interambulacrals, both perforate and im- 



8 perforate ; pi, first or proximal pinnule ; p2, second ; p3, third 



iAmb : 5 imperforate pinnule ; stc, subtentacular canal of anterior arm ; v>.p, water- 



i . , , i , j . , pores. (After Agassiz), x 23. 

 plates at the mterradial 



angles of the peristorue are taken by Agassiz for (Fig. CXIV.). 

 Stem long, smooth; root encrusting (Fig. CXIII. 2). FAMILY 2. 

 BOURGUETICRINIDAE. Pinnata in which the patina consists of 5 BB 



a.c. 



FIG. CXV. 



Bourgueticrinus. 1, B. aequalis (from Brit. Mus. E6705). 2, ventral view of same (from 

 E6706). 3, joint-surface of proxhnale (P), by which it articulates with adjoining colunmal (C). 

 4, vertical median section of B. ellipticus (after d'Orbigny). All x 4 diain. 



