32 PROCEEDINGS OF THE ACADEMY OF 



tubes of thin calcareous matter under the pseudo-ambulacra, and connecting 

 with the inner ends of the slits representing the so-called ovarian pores, are 

 also constructed as in Pentremites, excepting that here there are twelve of 

 these tubes under each pseudo-ambulacral area, while we have not seen more 

 than eight in any of the true Pentremites, nor more than four in Granatocrinus, 

 though we are not positively sure that these numbers will always be found 

 to hold good as generic distinctions. 



Compared with Codttster, the type under consideration is found to differ in 

 having only two of the slits mentioned in each of the anal and interradial 

 areas, iustead of about eight to sixteen ; while it has these slits equally in the 

 anal and interradial areas, instead of only in the latter, as in Codaster. It 

 also differs from that genus in having the internal folds or compressed tubers, 

 under the so-called pseudo-ambulacra, instead of extending under the whole 

 interradial areas. 



Since proposing this new genus, we have received from Mr. Wachsmuth a 

 fine specimen of another species of this type, which, although widely different 

 specifically, from the typical species, still exhibits very clearly the same gen- 

 eric characters, as 'will be seen from the following specific description : 



Codonites gracilis, D. and W. 



Body comparatively small, pentagonal-suboval, longer than wide, the widest 

 part being at the lower extremities of the so-called pseudo-ambulacral fields, 

 which terminate a little below the middle. Supplementary base small, very 

 short, or only appearing to be composed of a single tripartite joint of the col- 

 umn. Base low, or near three times as wide as high, expanding rapidiy up- 

 ward, and pentagonal in outline, as seen from below ; basal pieces of mode- 

 rate size, two pentagonal and one hexagonal. Radial pieces nearly twice as 

 long as wide, with a general oblong outline, though they are a little wider in 

 the middle than above or below; while the superior lateral angles are a little 

 truncated by ihe anal and interradial pieces, and the lower end is rounded, or 

 somewhat obtusely augular in outline at the middle ; all rather distinctly 

 convex below the middle ; so called pseudo-ambulacral sinuses narrow, and 

 very slightly tapering, extending down a little below the middle, where they 

 each terminate at a little pointed projection, which is directed horizontally 

 outward, so as to add to the pentagonal form of the body, as seen from above 

 or below. Anal piece of moderate size, wider and more obtuse below than 

 the interradials, and narrowed above, with a comparatively large anal opening, 

 nearly dividing it a little below the middle, where it is very contracted.* In- 



would require should be considered subradials, would alone be an objection to this con- 

 clusion. It is also worthy of note, that when these lower pieces are removed, we find the 

 next range of pieces above closed together, so as to form the bottom of the visceral 

 cavity, as true basals. Again in those species of Granatocrinus, like G. Nonooodii, with a 

 deep" concavity in the under side, we find the pieces corresponding to those Mr. Lyon 

 thinks are the subradials, as it were, pushed inward, and forming a little pyramid in the 

 bottom of the visceral cavity, precisely as we see the true basals in various types of 

 Crinoids with a sunken base" In addition to this, although adult specimens of the type 

 here under consideration have this lower part, supposed by Mr. L. to be the true base, 

 as solid as in the true Pentremites, young individuals show that it is actually composed of 

 five or six of the upper joints of the column enlarged and anchylosed together. Similar enlarge- 

 ments of tlie upper joints of the columns of various types of Crinoids are known to occur, 

 as, for instance, in Forbesiocrinils and its allies, in PoUriocrinites, Apiocritiites, etc. It is 

 true, that in these the enlarged part is not divided longitudinally by sutures, as in Pen- 

 tremites, Codonites, etc. This fact, however, will be seen to be of less importance when it 

 is remembered that there are examples of true Crinoids with the column longitudinally 

 divided ; such, for instance, as in Barycrinus, where we see the whole column divided into 

 five sections longitudinally, through its whole length. And here the five sutures of the 

 column coincide with those between the five true basal pieces, exactly as the three sutures 

 between the supplementary basal pieces in Codonites and Pentremites coincide with those 

 between their three, basal pieces. 



* We have several times thought we could see indications of sutures dividing the anal 

 piece of Codonites stelliformis and Granatocrinus Nonooodii into three pieces. That is, a 

 transverse suture at the anal opening, and a longitudinal one dividing the upper or inner 

 half into two pieces. Some casts of the interior of G. Nonooodii seem to snow this dis- 

 tinctly. 



[April, 



