110 Prof. P. M. Duncan on the 



tlie Triplecliinidae, A. Agass. It is the presence of a consider- 

 al)le number of fossil genera and a recent one, cliaracterized 

 by a large apical system with some of the radial plates enter- 

 ing the ring, a raised costulate ornamentation, without furrows 

 and pits in relation to the sutures, having Glyijliocyphns^ 

 Hairae, as the type, that necessitates the subdivision. This 

 group may become the Glyphocyphinte, and the remainder of 

 the genera, characterized by depressions, furrows, and pits 

 of the sutures, dowelling between the coronal plates and 

 a compact apical system, may enter the subfamily Temno- 

 pleuringe. It is advisable to raise the position of the Glypho- 

 stomata into a suborder of Regulares. 



According to Forbes's definition of Temnechinus and the 

 result of the examination of the fossil forms from Sind, by 

 ray colleague and myself, there can be no valid reason for 

 separating the genus from the Temnopleuringe, and it might 

 be urged that the genus has not more than a subgeneric value 

 in relation to Temnojjieurus. But when the admirable de- 

 scription of the recent Temnechinus maculatus, A. Agass. 

 (' Revision of the Echini,' p. 286, pi. viii.), is studied, it is 

 impossible not to agree with the author, and although there 

 are some anomalies present the form must, from our present 

 knowledge, enter Temnechinus. This being the case, it will 

 be found that there are some decided distinctions between 

 the species and any one of TemnopleuruSy such as the large 

 anal plate, the grooving around the tubercles, and the absence 

 of true pits and deep grooves at the angles of the sutures, the 

 grooving of the transverse sutures being slight. There is, 

 however, a very great difficulty to be overcome before 

 Temnechinus can come within the Temnopleuringe, and it is 

 the result of A. Agassiz's examination of the sides of the 

 coronal plates. In the " Report on the ' Blake ' Echini," 

 Mus. Comp. Zool. Harvard, Memoirs, vol. x. no. 1, xxiv. 

 pt. 1, 1883, p. 37. A. Agassiz wrote, " The specimens of diffe- 

 rent sizes which I have examined show no trace of pits nor 

 of this system of dowelling at the junction of plates." The 

 importance of this deficiency is great, and yet the peristome, 

 the spines, and some of the pedicellariaj are the same as those 

 of Temno2)leurus. It appears then that the modern Temne- 

 chinus must be decidedly separated from Temnopleurus j but 

 should the knob-and-socket arrangement of the union of the 

 plates be discovered, Temnechinus will enter the Temno- 

 pleurinai. It appears correct to associate the modern Trigono- 

 cidaris, A. Agass., with the Glyphocyphinee. 



The following observations upon some important structures 

 of species of Temnopleurus, Salmacisj Microcyphus, &c. were 



