STATE GEOLOGIST. 137 



5. D. staffncdis, Forbes . 



** Last segment of the thorax more or less united with the previous one, bearing very 

 small spines. 



6. D. longicornis, Herrick. 

 (u) Length under 2 mm. 



var. leptopus, Forbes. 

 (b) Length over 2 mm . 

 var. similis, Herrick. 

 B. Head enlarged. 



7. -D. laticeps, Sars. 



II. Form slender, elongate; head divided into two portions; antennse 

 long, slightly altered in the male. 



A. Antenna of male with a hook. 



8. D. gracilis, Sars. 



B. Antenna of ma'e without a hook. 



9. D, pallidus, Herrick.. 



(a) Antennae much longer than the body, inner rami of fifth pair of feet in the male 

 1-jointed. 



var. pallidus, Herrick. 



(b) Antennae little longer than the body, inner ramus of fifth feet bi-articulate. 

 var. sicilis, Forbes, 



Sp. 1. Diaptonius castor, Jurine. [Sars.] 



"Corporis forma sat robusta. Cephalothorax in femina postice parum antice vero magis 

 attenuatus, angulis laminarum segmenti ultimi obtusis. Segmentum 1-mum abdominale 

 absque mucrone laterali. Rami caudal es brevissimi segmento antecedente vix longiores 

 setis crassis et brevibus. Antennae 1-mi paris mediocris longitudinis reflexae segmentum 

 3-tiuni abdominale vix superantes, animali natante leviter arcuatae adque latei'a vergentes ; 

 articulus ultimus [?] antennas dextrae maris in hamulum exiens acuminatum. Ramus an- 

 tennarum 2-di paris exterior interiore parum modo longior, articulo ultimo quam antece- 

 dentibus 5 junctis breviore. Articulus ultimus pedum 5-ti paris in femina perrudimentaris 

 tuberculum solum minimum aculeo uno parvo instructum formans ; unguis intus curvatus 

 maximus validusque ; appendix interna indistincte bi-articulata longitudinem articuli 3-ti- 

 superans ; unguis terminalis pedis dextri maris longissimus leviterque arcuatus. Saccus 

 oviferus parva et multa continet ova colore castaneo. Color animalis variat ex fulvo, cae- 

 ruleo vel rubro. Longit, fem. interdum fere 3 mm. Habitat in aquis stagnantibus." 



The description quoted above from Sars does not agree with 

 Glaus' or Brady's account of the same species. From what Brady 

 says of the English Diaptomi one would conclude that the same 

 variations occur there as here. D. westwoodii, which he unites 

 with D. castor, is certainly as different from that species as our D. 

 stagnalis is from D. sanguineus. An actual comparison of specimens 

 will be necessary to clearly define the relation of the American and 

 European species. 



