40 AMERICAN JOURNAL 



toward GaJinla iu their 'roundod form, but are more closely 

 allied to the Siphonan'uhv. They cannot be affiliated to the Pa- 

 t('Jh\hr or Tt'i'(i(n'(hx'. The following species wore onumorated in 

 the paper alluded to, as having been definitely identified as be- 

 longing to this genus : ^4.. borcalis, ^Morton ; ^-1. sc.vsuIcatuSy 

 alreohis, j.)ateUif'orntis, and siibovatus, all of Meek and Ilayden. , 



The student who desires to pursue the subject farther, will do 

 well to consult the Conchologia Iconica and the list of species of 

 Si'j)honan'a given by llanley in the Proc. of the Zool. Society of 

 London, 1858, page 151. 



References to Plate 4. 



Fig. 8. a, side view of Siph. tJicrs/'ti'S, with the shell removed, 

 b. view of same in the shell, from below. 



Fig. 9. Nervous system of iSij>houan'a Triste7isis, Sby. 



Fig. 10. Dentition of Siplionaria [Siphonaria) altcrnata, Say. 



b, Rhaehidian tooth. 



a, section of 17th lateral. 



Fig. 11. Si'pJunian'd (^Lin'ola) jh'Itoiih's, Dall ex Cpr. 



a, from above, enlarged one-fourth. 



b, side view. 



Explanation of Plate 5. 



Fig. 1. Dentition of SipiJionan'a [Lin'ola) tristensis, Sby. 



1" a, side view of 45th tooth. 



1" c. 1st lateral 1" b, section of do. 



Fig. '2. Dentition of Sq^honan'a [Liriola) thcrsiti'S, Cpr. 



1' a, side view of 1st lateral. 



Fig. 8. Digestive and generative organs of SipJio)iaria tn'stcjisis, 

 Sby. From above. 



a, anus. j, jaw. 



b, genital bladder. * 1, 1, 1, boundar}' of liver. 



c, crop. 1, a, left adductor muscle, 

 g. genital papilla. r, a, right " '* 

 m, buccal mass. p, a, posterior adductor. 

 0, ovary, p, penis. 



r, rectum. s, salivary gland, 



st, stomach. t, testis. 



